CBSE Class 10

In this page, we are providing How do Organisms Reproduce Class 10 Extra Questions and Answers Science Chapter 8 pdf download. NCERT Extra Questions for Class 10 Science Chapter 8 How do Organisms Reproduce with Answers will help to score more marks in your CBSE Board Exams.

Class 10 Science Chapter 8 Extra Questions and Answers How do Organisms Reproduce

Extra Questions for Class 10 Science Chapter 8 How do Organisms Reproduce with Answers Solutions

Extra Questions for Class 10 Science Chapter 8 Very Short Answer Type

Question 1.
What is reproduction?  [CBSE 2012, 2016]
Answer:
Reproduction is the process by which an organism produces its young ones for perpetuation of its race.

Question 2.
Mention two modes of reproduction.  [CBSE 2013]
Answer:
The two modes of reproduction are-sexual reproduction and asexual reproduction.

Question 3.
Give one example for each of the following.
(а) Plants in which vegetative propagation occurs by grafting
(b) Plants in which vegetative propagation occurs by leaves  [CBSE 2012]
Answer:
(a) Rose, grapes can be vegetatively propagated by grafting.
(b) Bryophyllum can be vegetatively propagated by leaves.

Question 4.
Name a plant that has lost the capacity to produce seed. How can it reproduce?  [CBSE 2013]
Answer:
Banana. It can reproduce by vegetative propagation.

Question 5.
Name any two consequences of unsafe sex.  [CBSE 2012]
Answer:
The two consequences of unsafe sex are:

1. Transmission of sexually transmitted diseases
2. Unwanted pregnancy

Question 6.
Name the hormone, the secretion of which is responsible for dramatic changes in appearance in girls when they approach 10-12 years of age.  [CBSE 2008]
Answer:
Oestrogen

Question 7.
Mention the modes of reproduction used by
(a) Amoeba
(b) Planaria  [CBSE 2009]
Answer:
(a) Amoeba – Binary fission
(b) Planaria – Regeneration

Question 8.
Name any two types of asexual reproduction.  [CBSE 2009]
Answer:

1. Fission
2. budding

Question 9.
State the method used for growing rose plants.  [CBSE 2009]
Answer:
Vegetative propagation

Question 10.
State which type of method is used for growing Jasmine plant.  [CBSE 2009]
Answer:
Layering.

Extra Questions for Class 10 Science Chapter 8 Short Answer Type I

Question 1.
Write the full form of DNA. Where is it located? What does it consist of?  [CBSE 2013]
Answer:
DNA = Deoxyribo Nucleic Acid. It is located in the nucleus of the cell. It consists of nucleotides which make nucleic acids.

Question 2.
Mention the information source for making proteins in the cell. What is the basic event in reproduction?  [CBSE 2008, 2009]
Answer:
The information source for making proteins in the cell is deoxyribo nucleic acid (DNA). The basic event in reproduction is the replication of DNA and cell division.

Question 3.
How does the creation of variation in a species promote survival?  [CBSE 2013]
Answer:
Creation of variation increases the probability or chances of survival of some members of the population under adverse conditions. This ensures the survival of the species under unfavourable conditions.

Question 4.
Protozoans reproduce by binary fission as well as multiple fission. Which process is better and why? Give your opinion.  [CBSE 2011]
Answer:
Multiple fission is better than binary fission because it produces many daughter cells inside a protective structure called cyst which ensures their survival under adverse conditions.

Question 5.
Name the kind of organisms that reproduce by spore formation. How will an organism be benefitted if it reproduces through spores?  [CBSE 2013]
Answer:
Rhizopus (Fungus) reproduces by spore formation. The organism is benefitted because the spores are covered by thick walls that protect them until they come in contact with a moist surface and begin to grow.

Question 6.
Compare the vegetative propagation in Bryophyllum and money plant.  [CBSE 2011]
Answer:
Bryophyllum reproduces by the adventitious buds present on the margins of its leaves.
Money plant reproduces by stem cutting which can produce the whole plant when placed in moist soil.

Question 7.
List any two pubertal changes that appear in both boys and girls.  [CBSE 2013]
Answer:
The two pubertal changes which appear in both boys and girls are:

1. The skin becomes oily and pimples appear
2. Pubic hairs appear

Question 8.
(a) Specify the events which occur in the reproductive system of a human female.
(i) if egg is fertilised
(ii) if egg is not fertilised.
(b) Mention the changes that take place in uterus in both the above events.  [CBSE 2012]
Answer:
(a) (i) Pregnancy
(ii) Menstruation

(b) If the egg gets fertilised then the wall of the uterus becomes thick and spongy with a rich supply of blood vessels to receive the fertilised zygote.

If the egg does not get fertilised then the blood vessels in the wall of the uterus along with the spongy uterine tissue is shed in the form of blood and mucus through the vagina.

Question 9.
Prenatal sex determination has been prohibited by law, state two reasons.  [CBSE 2011]
Answer:
Prenatal sex determination has been prohibited by law to:

1. Check the female foeticide
2. Prevent the decline in female sex ratio

Question 10.
How can pregnancy be prevented surgically?  [CBSE 2012]
Answer:
The pregnancy can be prevented surgically by:

• Vasectomy: The vas deferens of male is blocked to prevent sperm transfer.
• Tubectomy: The fallopian tube of female is blocked to prevent egg to reach uterus.

Extra Questions for Class 10 Science Chapter 8 Short Answer Type II

Question 1.
Mention any three advantages of variation in individuals.  [CBSE 2013]
Answer:
The advantages of variation are:

1. Forms the basis of evolution
2. Enables survival under adverse conditions
3. Enables the organisms to adapt.

Question 2.
Identify among the following organisms, which reproduce by sexual and which by asexual methods?
Amoeba, Human beings, Whale, Hydra, Spirogyra, Dog  [CBSE 2013]
Answer:
Sexual reproduction – Human beings, Whale, Dog
Asexual reproduction – Amoefea, Hydra, Spirogyra

Question 3.
How do the following plants reproduce?
(a) Potato
(b) Sweet Potato
(c) Ginger  [CBSE 2013]
Answer:
(a) Potato by tuber
(b) Sweet Potato by root
(c) Ginger by rhizome.

Question 4.
Explain budding in Hydra with the help of diagrams only. [CBSE 2013]
Answer:

Question 5.
Differentiate between reproduction and regeneration. Name any two organisms which grow by regeneration.  [CBSE 2012]
Answer:
Reproduction is the process by which an organism produces its young ones for perpetuation of its race. Some organisms have the ability to form new organisms from the pieces of its body which has been cut into different pieces. This process by which new organisms develop from the parts of an organism is called regeneration. Planaria and Hydra have the ability of regeneration.

Question 6.
Name the female reproductive part of a flower. Which part of a flower develops into a seed and a fruit? Where are the male germ cell and female gamete present in the flower? [CBSE 2011]
Answer:
Female reproductive part of a flower is carpel. Ovule develops into a seed and a fertilised ovary develops into fruit. Male germ cells are present in the pollen grain of a flower. Female gamete are present in the ovules located in ovary of a flower.

Question 7.
(a) Trace the path of sperms from where they are produced in human body to the exterior.
(b) Write the functions of secretions of prostate gland and seminal vesicle in humans.  [CBSE 2013]
Answer:
Sperm comes out from testis into the vas deferens and pass through the urethra before ejaculation. The secretions of seminal vesicle and prostrate glands provide nutrition to the sperms and also facilitate their transport.

Question 8.
Name one sexually transmitted disease each caused due to bacterial infection and viral infection. How can these be prevented? [CBSE 2008]
Answer:

1. Gonorrhoea caused by bacteria
2. AIDS caused by HIV (Human immune deficiency virus)

They can be prevented by using condoms and safe sexual practices.

Question 9.
Name the organ where sperms are produced and name the hormone produced by it. Why do sperms have a tail but ovum does not have it?  [CBSE 2013]
Answer:
Sperms are produced in the testes. The hormone produced by testes is testosterone. The sperms have a tail to enable them to swim and move towards the non-motile female gamete.

Question 10.
What is reproduction? Mention the importance of DNA copying in reproduction.  [CBSE 2008]
Answer:
Reproduction is the process by which organisms produce their own kind. The DNA copying is important because:

• It ensures the transmission of characteristics from parents to their offsprings.
• Variations are created during DNA copying which increase the chances of survival of the species and in the evolution of new life forms.

Question 11.
Explain how, offspring and parents of organisms reproducing sexually have the same number of chromosomes. [NCERT Exemplar]
Answer;
The process of cell division called meiosis halves the number of chromosomes present in the cell of an organism. The gametes produced as a result of meiosis, fuse during sexual reproduction and restore the number of chromosomes in the offsprings of the individual.

Question 12.
Why does bread mould grow profusely on a moist slice of bread rather than on a dry slice of bread?  [NCERT Exemplar]
Answer:
Moist slice of bread is able to provide both moisture and nutrients needed for the growth of the hyphae. Dry slice of bread is able to provide only the nutrients but not moisture, so the hyphae do not grow on the dry slice of bread.

Question 13.
Would a Planaria cut vertically into two halves regenerate into two individuals? Complete Figure D and E by indicating the regenerated regions.  [NCERT Exemplar]

Answer:
Yes, shaded part in Figures D and E represent the regenerated halves.

Question 14.
From the internet, gather information about the chromosome numbers of five animals and five plants. Correlate the number with the size of organism and answer the following questions.
(а) Do larger organisms have more number of chromosomes/cells?
(b) Can organism with fewer chromosomes reproduce more easily than organisms with more number of chromosomes?
(c) More the number of chromosomes/cells greater is the DNA content. Justify.  [NCERT Exemplar]
Answer:
(a) No, there is no relationship between size of the organism and its chromosome number.
(b) No, process of reproduction follows a common pattern and is not dependent on the number of chromosomes.
(c) Yes, if there are more chromosomes in a cell, the quantity of DNA will also be more because the major component of the chromosome is DNA.

Question 15.
In tobacco plant, the male gametes have twenty four chromosomes. What is the number of chromosomes in the female gamete? What is the number of chromosomes in the zygote?  [NCERT Exemplar]
Answer:
Number of chromosomes in female gamete is 24.
Number of chromosomes in zygote is 48.

Question 16.
How are general growth and sexual maturation different from each other?  [NCERT Exemplar]
Answer:
General growth comprises of the different types of developmental process in the body like increase in height, weight gain, changes in shape and size of the body. Sexual maturation refers to the specific changes which occur at puberty like cracking of voice, new hair patterns, development of breast in female, etc.

Question 17.
Trace the path of sperm during ejaculation and mention the gland and their functions associated with the male reproductive system.  [NCERT Exemplar]
Answer:
Sperm comes out from testis into the vas deferens and pass through the urethra before ejaculation. The secretions of seminal vesicle and prostate glands provide nutrition to the sperms and also facilitate their transport.

Question 18.
What changes are observed in the uterus if fertilisation does not occur?  [NCERT Exemplar]
Answer:
If fertilisation does not occur then the thick and spongy lining of the uterus slowly breaks and comes out through the vagina in the form of blood and mucus.

Question 19.
What changes are observed in the uterus subsequent to implantation of young embryo?  [NCERT Exemplar]
Answer:
After implantation, a special tissue called placenta develops which connects embryo to the uterine wall. Placenta provides nutrients and oxygen to the embryo which are obtained from the rich blood supply of the uterine wall.

Extra Questions for Class 10 Science Chapter 8 Long Answer Type

Question 1.
Why are budding, fragmentation and regeneration all considered as asexual types of reproduction? With neat diagrams explain the process of regeneration in Planaria.  [NCERT Exemplar]

Answer:
They are considered as asexual types of reproduction as all of them involve a single parent and no fusion of gametes take place in them.

Question 2.
Write two points of difference between asexual and sexual types of reproduction. Describe why variations are observed in the offspring formed by sexual reproduction.  [NCERT Exemplar]
Answer:
Asexual Reproduction:

1. Single parent is involved.
2. No fusion of gametes occur.
3. Progeny is genetically identical to the parent.
   For example, Fission in Amoeba

Sexual Reproduction:

1. Two parents are involved.
2. Fusion of gametes occurs.
3. Variations occur in the progeny.
   For example, Human beings

Fusion of gametes occurs during sexual reproduction. The gametes contain the same number of chromosomes but their DNA is not identical so variations arise among the offsprings.

Question 3.
Distinguish between pollination and fertilisation. Mention the site and product of fertilisation in a flower. Draw a neat, labelled diagram of a pistil showing pollen tube growth and its entry into the ovule.   [NCERT Exemplar]
Answer:
Pollination: The transfer of pollen grains from the anther to the stigma of a flower is called pollination.
Fertilisation: The process of fusion of male and female gametes to form a zygote is called fertilisation.
The site of fertilisation is ovule. The product of fertilisation is zygote.

Question 4.
Distinguish between a gamete and zygote. Explain their roles in sexual reproduction.  [NCERT Exemplar]
Answer:
The sex cell or germ cell in sexual reproduction is called gametes. There are two types of gametes, male and female. A male and a female gamete fuse with each other during fertilisation to form a zygote.

The gametes possess characters of their parents in their DNA and their fusion brings characters of both parents into one zygote cell. Zygote is the first cell of the next generation which divides to form an embryo which subsequently grows into a new individual.

Question 5.
Draw the diagram of a flower and label the four whorls. Write the names of gamete producing organs in the flower. [NCERT Exemplar]
Answer:
Male gamete forming part – anther/stamen
Female gamete forming part – pistil/ovary/ovule

Question 6.
What is placenta? Mention its role during pregnancy.  [NCERT Exemplar, CBSE 2017]
Answer:
A disc shaped special tissue connection between embryo and uterine wall is called placenta. It contains villi on the embryo’s side of the tissue which are surrounded by blood spaces on the mother’s side. Roles of placenta are:

• It provides a large surface area for glucose and oxygen to pass from mother to the embryo.
• Removes waste substances produced by the developing embryo.

Question 7.
What are various ways to avoid pregnancy? Elaborate any one method.  [NCERT Exemplar]
Answer:
(a) Contraceptive methods are used to avoid pregnancy which are of the following types:

• Mechanical
• Drugs (as pills)
• Loop or copper T and
• Surgical method.

(b) Surgical Methods:

• Vasectomy: The vas deferens of male is blocked to prevent sperm transfer.
• Tubectomy: The fallopian tube of female is blocked to prevent egg to reach uterus.
• Copper-T or loop is placed in uterus to prevent pregnancy.

Question 8.
How does fertilisation take place? Fertilisation occurs once in a month. Comment.  [NCERT Exemplar]
Answer:

• Sperm enters through the vaginal passage during sexual intercourse and moves upwards.
• Egg released from the ovary reaches the fallopian tube (oviduct).
• Sperm encounters egg in the oviduct and fertilisation takes place. Fallopian tube (oviduct) is the site of fertilisation.
• An egg is released once every month by the ovary as usually one ovum (egg) is released by an ovary during each cycle.

Question 9.
Reproduction is essentially a phenomenon that is not for survival of an individual but for the stability of a species. Justify.  [NCERT Exemplar, CBSE 2017]
Answer:

• The energy needed for survival of the organisms is obtained by them from life processes such as nutrition and respiration.
• Reproduction needs a lot of energy.
• Genetic material is transferred from one generation to the next as a result of reproduction through DNA copying.
• DNA copying takes place with high constancy and considerable variations, that is, advantages to the species for stability in the changing environment.

Question 10.
Describe sexually transmitted diseases and mention the ways to prevent them.  [NCERT Exemplar]
Answer:
Sexually transmitted diseases are infectious diseases transmitted during sexual contact. Various agents like bacteria and virus cause these diseases. For example, Gonorrhoea, syphilis, genital herpes, chlamydiasis, genital warts, trichomoniasis, hepatitis-B and HIV-AIDS are sexually transmitted diseases.

Principles to follow to prevent such infections:

• Avoid sex with unknown partners/multiple partners,
• Always use condoms during coitus.
• Use of mechanical barrier like condom prevents transmission of infection
• In case of doubt, go to a qualified doctor for early detection and get complete treatment if diagnosed with disease.

How do Organisms Reproduce HOTS Questions With Answers

Question 1.
Ravi took three bread slices and kept them in the following conditions:
(a) Slice 1 in a dried and dark place
(b) Slice 2 in moist and dark place
(c) Slice 3 in refrigerator under moist conditions
What would he observe in each of the above conditions?  [CBSE 2013]
Answer:
(a) No spores will be formed in Slice 1 as moisture is not there.
(b) Fungal hyphae develop as white cottony mass and bear sporangia having spores in Slice 2 as they get both favourable conditions of moisture and darkness.
(c) No spores will be formed in Slice 3 as lower temperature in refrigerator is not favourable for their formation.

Question 2.
Small piece of root tissue was taken from the rose plant and placed in a nutrient medium. Each root tissue produced a new rose plant. Name the reproductive process involved. What type of genes will be possessed by the new rose plant?  [CBSE 2012]
Answer:
The reproductive process involved is called as tissue culture. The new rose plant has the genes which are identical to the parent rose plant.

Question 3.
A student noticed that an organism by mistake was cut into parts. After sometime, both parts developed into new individuals.
(a) Name the mode of reproduction used by the organism.
(b) State the type of cells which carry this process.
(c) State two examples of organisms which multiply by this process.  [CBSE 2013]
Answer:
(а) The mode of reproduction used by the organism is regeneration.
(b) It is carried out by specialised which can proliferate and make a large number of cells by cell division.
(c) Hydra and Planaria.

Question 4.
Explain why fertilisation is possible only if copulation takes place during the middle of menstrual cycle?  [CBSE 2012]
Answer:
The release of ovum occurs around the middle of the menstrual cycle i.e., on 14th day. So, the chances of meeting of sperm and egg are increased during this period. Hence, if copulation takes place during the middle of menstrual cycle, the chances of fertilisation are more.

Question 5.
Name the plant hormones which help/promote
(i) Cell division
(ii) Growth of stem  [CBSE 2009]
Answer:
(i) Cytokinins help in cell division.
(ii) Auxins help in the growth of the stem.

Extra Questions for Class 10 Science Chapter 8 Value Based Questions

Question 1.
Rohini’s parents received a proposal for her marriage from a boy living in U.K. Before everything could get finalised, Rohini asked her parents to ask the boy to get his blood test report.
(a) Do you think it was right on the part of Rohini’s parents to do so?
(b) What moral values did Rohini showed?
(c) Name two STD’s along with their causative organism.  [CBSE 2013]
Answer:
(a) Yes, it was right on Rohini’s parents to do so because blood reports would be able to indicate whether the person has any disease, any sexually transmitted disease or is free of them.

(b) Rohini is intelligent, cautious, responsible and vigilant.

(c) Two sexually transmitted diseases are:

• AIDS caused by HIV
• Gonorrhoea caused by Neisseria gonorrhoea

In this page, we are providing Life Processes Class 10 Extra Questions and Answers Science Chapter 6 pdf download. NCERT Extra Questions for Class 10 Science Chapter 6 Life Processes with Answers will help to score more marks in your CBSE Board Exams.

Class 10 Science Chapter 6 Extra Questions and Answers Life Processes

Extra Questions for Class 10 Science Chapter 6 Life Processes with Answers Solutions

Extra Questions for Class 10 Science Chapter 6 Very Short Answer Type

Question 1.
What will happen to a plant if its xylem is removed?  [CBSE 2009]
Answer:
Xylem helps in the transport of water and minerals to the various parts of the plant. If xylem is removed it would ultimately lead to the death of the plant.

Question 2.
Name the green dot like structures in some cells observed by a student when a leaf peel was viewed under a microscope. What is the green colour due to?  [CBSE 2010]
Answer:
The green dots like structures seen are the chloroplasts. The green colour is due to the pigment called chlorophyll.

Question 3.
Give one reason why multicellular organisms require special organs for exchange of gases between their body and their environment.  [CBSE 2010]
Answer:
Simple diffusion is not sufficient for the exchange of gases in multicellular organisms as all their cells are not in direct contact with the environment. So, they require special organs for exchange of gases between their body and their environment.

Question 4.
What process in plants is known as transpiration?  [CBSE 2008]
Answer:
The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration.

Question 5.
What is osmoregulation?  [CBSE 2006]
Answer:
The maintenance of optimum concentration of water and salts (electrolytes) in the body fluids is called as osmoregulation.

Question 6.
Why is carbon dioxide mostly transported in dissolved form?
Answer:
Carbon dioxide is mostly transported in the dissolved form as it is more soluble in water.

Question 7.
When we breathe out, why does the air passage not collapse?  [CBSE 2014]
Answer:
Rings of cartilage present on trachea prevent it from collapsing during the passage of air.

Question 8.
Herbivores have longer small intestine while carnivores have shorter small intestine. Give reason.  [CBSE 2014]
Answer:
Herbivores have a longer small intestine compared to the carnivores to allow time for the cellulose present in the grass to get digested.

Question 9.
Mention the respiratory unit of lungs and excretory unit of kidneys.  [CBSE 2014]
Answer:
The respiratory unit of lungs are alveoli and excretory unit of kidneys are nephrons.

Question 10.
Some organisms derive nutrition from plants or animals without killing them. What are these organisms called? Write one example.  [CBSE 2014]
Answer:
They are called parasites, e.g. Cuscuta and tapeworm are the parasites of plants and animals respectively.

Question 11.
What are the major constituents of urine?  [CBSE 2008]
Answer:
Urine is an aqueous solution of water, urea, chloride, sodium, potassium, creatinine and other dissolved ions, inorganic and organic compounds (proteins, hormones, and metabolites).

Question 12.
Where does the urine produced by the kidneys get stored?  [CBSE 2006]
Answer:
Urinary bladder.

Question 13.
How does transpiration help in upward transport of substances?  [CBSE 2008]
Answer:
Transpiration creates a suction pressure which pulls up water along with the minerals through the xylem.

Question 14.
When the right atrium contract, blood flows from it to which part of the heart?  [CBSE 2007]
Answer:
Right ventricle.

Question 15.
State the functions of the following:
(i) Blood
(ii) WBC  [CBSE 2011, 2012]
Answer:
Function of RBC – To carry oxygen to various parts of the body.
Function of WBC – To protect the body against both infectious diseases and foreign invaders.

Question 16.
Write the functions of the two upper chambers of the human heart.  [CBSE 2011]
Answer:
The right atrium receives deoxygenated blood from various parts of the body through the vena cava.
The left atrium receives the oxygenated blood from the lungs through the pulmonary artery.

Question 17.
Leakage of blood from vessels reduces the efficiency of pumping system. How is the leakage prevented? [CBSE 2010, 2011]
Answer:
Leakage is prevented by the blood platelets present in the blood which help in clotting the blood at the site of injury.

Question 18.
Which mechanism plays an important role in transportation of water in plants
(i) During daytime
(ii) At night?  [CBSE 2011, 2012]
Answer:
During daytime – Transpiration; At Night – Root pressure.

Question 19.
Why are valves present in heart and the veins?   [CBSE 2010,2011]
Answer:
Valves present in the heart does not allow the blood to flow backwards when the atria or ventricles contracts. Valves are present in the veins to prevent the back flow of blood in the veins as it travels at very slow rate in the veins.

Extra Questions for Class 10 Science Chapter 6 Short Answer Type I

Question 1.
How are the fats digested in our bodies? Where does this process take place?  [CBSE 2011]
Answer:
Bile juice produced by the liver breaks down the large fat globules into smaller globules by the process of emulsification. These small globules are then digested by the fat digesting enzymes. This process takes place in the small intestine.

Question 2.
State the function of the epiglottis.  [CBSE 2004]
Answer:
Epiglottis covers the opening of the wind pipe (the glottis) and prevents the entry of food into the wind pipe during swallowing.

Question 3.
The breathing cycle is rhythmic, whereas exchange of gases is a continuous process. Comment upon this statement.
Answer:
Some volume of air called as residual volume is left behind in the lungs even after forceful breathing out of air. This helps to provide sufficient time for oxygen to be absorbed and for carbon dioxide to be released. Even in the absence of continuous breathing, the exchange of these gases is continuous. Hence, breathing cycle is rhythmic, whereas exchange of gases is a continuous process.

Question 4.
What are the end products formed during fermentation in yeast? Under what condition a similar process takes place in our body that lead to muscle cramps?  [CBSE 2010]
Answer:
The end products formed during fermentation in yeast are ethanol and carbon dioxide. A similar process occurs in the muscles and produces lactic acid during anaerobic respiration in the muscles. Accumulation of lactic acid in the muscle cells lead to muscular cramps.

Question 5.
Give Reasons:
(a) Rings of cartilage are present in the trachea.
(b) Lungs always contain a residual volume of air.  [CBSE 2013]
Answer:
(a) The walls of trachea have rings of cartilage on them which prevent it from collapsing.
(b) The volume of air left behind in the lungs even after forceful breathing out of air is called as residual volume. This helps to provide sufficient time for oxygen to be absorbed and for the carbon dioxide to be released.

Question 6.
State in brief the role of lungs in the exchange of gases.  [CBSE 2012]
Answer:
Lungs have alveoli which provide a larger surface for exchange of gases and are richly supplied with blood vessels to enable faster exchange. So, lungs help in providing oxygen to various tissues of the body and removal of carbon dioxide from the body.

Question 7.
What is the basic unit of kidney called? Why is it composed of very thin blood capillaries?  [CBSE 2015]
Answer:
The basic unit of kidney is called nephron. It is composed of a cluster of very thin blood capillaries as they help in filtration of blood and remove the nitrogenous wastes from the body in the form of urine.

Question 8.
How does the plant get rid of excretory products?  [CBSE 2009]
Answer:
Excess oxygen and carbon dioxide removed through stomata.
Plant waste products are also removed by:

• Storage in cellular vacuoles
• Storage in leaves that fall off
• Storing as resins and gums in old xylem
• By excreting into the soil around them.

Question 9.
Tabulate two differences between renal artery and renal vein. [CBSE 2009]
Answer:
Renal Artery

1. Blood in renal artery contains glucose, oxygen and cellular waste products.
2. It takes blood towards the kidney.

Renal Vein:

1. Blood in renal vein is filtered, and is free from cellular waste and any other impurities.
2. It takes blood away from the kidney towards the heart.

Question 10.
(a) What is the main toxic waste that kidney filters from the blood?
(b) Name any two substances which are selectively reabsorbed from the tubules of a nephron.  [CBSE 2010, 2012]
Answer:
(a) Urea is the main excretory product removed by the kidneys of human beings.
(b) The substances selectively reabsorbed by the kidneys are water, glucose, electrolytes, etc.

Question 11.
What is excretion? How do unicellular organisms remove their wastes?  [CBSE 2012]
Answer:
Removal of metabolic wastes from the body is called as excretion. Many unicellular organisms remove metabolic wastes from the body surface into the surrounding water by simple diffusion.

Question 12.
Write a function of (a) blood vessels (b) blood platelets.  [CBSE 2008]
Answer:
(a) Blood vessels help in carrying blood to various parts of the body.
(b) Blood platelets help in the clotting of blood at the point of injury to prevent non-stop bleeding.

Question 13.
How are water and minerals absorbed by the plant?  [CBSE 2010]
Answer:
The water and minerals in the soil are absorbed by plants with the help of root hairs present on their roots. Root hairs provide a larger surface area for absorption.

Question 14.
What are capillaries? Sate the function performed by them.  [CBSE 2012]
Answer:
The capillaries are one-cell thick, small blood vessels which help in the exchange of materials between the blood and the surrounding tissues.

Question 15.
Mention the two main components of the transport system in plants. State one function of each one of these components.  [CBSE 2010, 2011]
Answer:
The two main components of the transport system in the plants are xylem and phloem. Xylem helps to transport water and minerals to various parts of the plant. Phloem helps to carry food from leaves to the various parts of the plant.

Question 16.
During one cycle how many times does blood go to the heart of fish and why?  [CBSE 2010]
Answer:
The blood passes only once through the heart in one cycle in fishes because the two-chambered heart of the fishes pump the blood to gills for oxygenation. The blood from gills is then directly passed to the various parts of the body in the fishes.

Question 17.
What would be the consequences of deficiency of haemoglobin in our bodies?  [CBSE 2012]
Answer:
Haemoglobin helps in transport of oxygen to the body parts. Deficiency of haemoglobin will affect transport of oxygen and the person will suffer from improper metabolism, weakness, fatigue and pain.

Question 18.
Name the following:
(а) The process in plants that links light energy with chemical energy.
(b) Organisms that can prepare their own food.
(c) The cell organelle where photosynthesis occurs.
(d) Cells that surround a stomatal pore.
(e) Organisms that cannot prepare their own food.
(f) An enzyme secreted from gastric glands in stomach that acts on proteins. [NCERT Exemplar]
Answer:
(a) Photosynthesis
(b) Autotrophs
(c) Chloroplast
(d) Guard cells
(e) Heterotrophs
(f) Pepsin

Question 19.
“All plants give out oxygen during the day and carbon dioxide during night”. Do you agree with this statement? Give reason.  [NCERT Exemplar]
Answer:
The rate of photosynthesis is higher than the rate of respiration during the daytime, so the net result is the evolution of oxygen. In the absence of photosynthesis at night, only respiration occurs in the plants so carbon dioxide is released at night.

Question 20.
How do the guard cells regulate opening and closing of stomatal pores?  [NCERT Exemplar]
Answer:
The entry of water into the guard cells of the stomata causes an increase in turgor pressure in the guard cells which leads to opening of the stomata. The loss of water from the guard cells results in their shrinking and closes the stomata.

Question 21.
Two green plants are kept separately in oxygen free containers, one in the dark and the other in continuous light. Which one will live longer? Give reasons.  [NCERT Exemplar]
Answer:
Plant kept in continuous light will perform photosynthesis and release oxygen for its respiration. Hence, it will live longer than the plant kept in the dark.

Question 22.
If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer.  [NCERT Exemplar]
Answer:
During the day time the plants take in carbon dioxide and release oxygen as a by product of photosynthesis. Release of carbon dioxide and taking in air during the daytime means that either the rate of photosynthesis is too low or its not occurring at all.

Question 23.
Why do fishes die when taken out of water? [NCERT Exemplar]
Answer:
Fishes take water from mouth and send it to the gills which are richly supplied with blood capillaries for absorbing the oxygen dissolved in water. But the fishes cannot absorb gaseous oxygen, so they die soon after they are taken out of water.

Question 24.
Is ‘nutrition’ a necessity for an organism? Discuss.  [NCERT Exemplar]
Answer:
Nutrition (food) is a necessity for an organism as

• It provides energy for the various metabolic processes in the body.
• It is essential for the growth and repair of various cells and tissues.
• It helps to provide resistance against various diseases.

Question 25.
What would happen if green plants disappear from the Earth?  [NCERT Exemplar]
Answer:
The green plants are the source of energy for the entire organisms on the Earth. Herbivores depend directly on the plants while the carnivores and omnivores depend either directly or indirectly on plants. So, all the organisms will die due to starvation if all the green plants disappear from the Earth.

Question 26.
Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long? Give reasons for your answer.  [NCERT Exemplar]
Answer:
This plant will not remain healthy for a long time because the stomata will get blocked, so plant

• Will not get carbon dioxide for photosynthesis.
• Will not get oxygen for respiration.
• Will not be able to do transpiration which will in turn affect the upward transport of water and minerals.

Extra Questions for Class 10 Science Chapter 6 Short Answer Type II

Question 1.
(a) Explain why the rate of photosynthesis is low both at lower and higher temperatures.
(b) Is green light most or least useful in photosynthesis and why?  [CBSE 2005]
Answer:
(a) The reactions occurring during the process of photosynthesis is under the control of enzymes, which work under an optimum range of temperature only. The very high temperatures as well as very low temperatures decrease the activity of the enzymes. So, the rate of photosynthesis is low both at lower and higher temperatures.
(b) Chlorophyll does not absorb the green light, so the green light is least useful in photosynthesis.

Question 2.
Draw a well labelled diagram of stomata. List two functions of stomata.  [CBSE 2011]
Answer:
The function of stomata are:
(a) Help in the exchange of gases like carbon dioxide and oxygen from the leaves of the plants.
(b) Help in the transport of water, minerals and food materials in plants by transpiration.
(c) Transpiration occurring through stomata on leaves helps in cooling of leaf surface.

Question 3.
Explain how the products of photosynthesis and other substances are translocated in plants?  [CBSE 2015]
Answer:
Translocation is the transport of soluble products of photosynthesis through phloem. Sucrose is transferred into sieve tubes of phloem via the companion cells using energy from ATP. This increases the osmotic pressure inside the sieve tubes which causes movement of water into the sieve tubes from the adjacent xylem. This pressure helps in translocation of material in the phloem to tissues which have less pressure.

Question 4.
Write three events which occur during the process of photosynthesis.  [CBSE 2015]
Answer:
The three events which occur during photosynthesis are:

1. Absorption of light energy of chlorophyll.
2. Conversion of light energy to chemical energy + splitting of water molecules into hydrogen and oxygen.
3. Reduction of carbon dioxide to carbohydrates.

Question 5.
Explain why the transportation of materials is necessary in animals?  [CBSE 2014]
Answer:
The transportation system is necessary to transport the various nutrients and gases to and from the various parts of the body. It also helps in removing the wastes from the body of the organisms. The various life processes are maintained and carried out due to an efficient transport system in animals.

Question 6.
Plants absorb water from the soil. Explain how does the water reach the tree top?  [CBSE 2014]
Answer:
There are two ways for the transport of water in plants:
(а) By root pressure: The cells of root in contact with soil actively take up ions which creates a difference in ion concentration between the root and the soil. Water moves into the root from the soil to eliminate this difference, creating a column of water that is steadily pushed upwards.

(b) By transpiration pull: Loss of water from stomata by transpiration gets replaced by the xylem vessels in the leaf which creates a suction to pull water from the xylem cells of the roots. This strategy is used during day time and helps to transport water to the highest points of the plant body.

Question 7.
State the function of the following in the alimentary canal.
(a) Liver
(b) Gallbladder
(c) Villi   [CBSE2014]
Answer:
(a) Liver: Helps in detoxification of harmful chemicals. Produces bile juice which helps in digestion of fats.
(b) Gall bladder: Helps in the storage of bile juice released from the liver.
(c) Villi: Helps to increase the surface area of the small intestine and aid in absorption of the digested nutrients.

Question 8.
(a) How does exchange of respiratory gases—oxygen and carbon dioxide take place between tissues and blood in human beings?
(b) Name the respiratory pigment in humans. Where is it found?  [CBSE 2014]
Answer:
(a) The arteries have oxygenated blood having oxygen at higher pressure to that present in the tissues. Carbon dioxide is present at a higher pressure inside the tissues. The oxygen is thus exchanged at the tissue surface with carbon dioxide in order to supply oxygen to the tissues of the body.

(b) Haemoglobin is the respiratory pigment in humans which is present in the red blood cells.

Question 9.
Explain giving any three reasons the significance of transpiration in plants.   [CBSE 2014]
Answer:
The significance of transpiration is:

1. Absorption and upward movement of water and minerals.
2. It also helps in temperature regulation by cooling the leaf surface.
3. It helps to maintain the shape and size of the cells.

Question 10.
Mention the pathway of urine starting from the organ of its formation. Name four substances which are reabsorbed from the initial filtrate in the tubular part of the nephron.  [CBSE 2014]
Answer:
The urine formed in the kidney moves through the ureters to the urinary bladder. Ureters takes urine into the urinary bladder where it is stored until it is released through the urethra. Release of urine is under nervous control.

Glucose, amino acids, salts and water are reabsorbed from the initial filtrate in the tubular part of the nephron.

Question 11.
Major amount of water is selectively reabsorbed by the tubular part of nephron. On what factor does the amount of water reabsorbed depends?  [CBSE 2010, 2011, 2012]
Answer:
The amount of water reabsorbed by the tubular part of nephron depends on two factors:

1. The amount of nitrogenous and other excretory wastes present in the body.
2. The amount of excess water present in the body.

Question 12.
State the functions of
(a) Renal artery
(b) kidney
(c) urinary bladder.  [CBSE 2012]
Answer:
(a) Renal artery: It brings blood having nitrogenous wastes to nephrons for filtration.
(b) Kidney: It help to filter the nitrogenous and other wastes from the blood.
(c) Urinary bladder: Stores urine until it is eliminated.

Question 13.
(a) Write the important functions of the structural and functional unit of kidney.
(b) Write any one function of an artificial kidney.  [CBSE 2011]
Answer:
(a) The structural and functional units of kidney are the nephrons which help in filtration, reabsorption and secretion. They help to eliminate the wastes from the body.

(b) Artificial kidneys help to remove the harmful nitrogenous wastes from the body of a patient whose kidneys are not functioning properly.

Question 14.
How is urine produced?  [CBSE 2011]
Answer:
The urine formation involves three steps:
(a) Glomerular filtration: Nitrogenous wastes, glucose water, amino acid are filtered from the blood in blood capillaries into Bowman Capsule of the nephrons.

(b) Selective reasbsorption: Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water are selectively reabsorbed back by capillaries surrounding the nephrons.

(c) Tubular secretion: Some ions like K⁺, H⁺, etc. are secreted into the tubule which opens up into the collecting duct.

Question 15.
Blood does not clot in the blood vessels. Give reasons.  [CBSE 2009]
Answer:
Blood does not clot inside the blood vessels because the chemical which causes the blood to clot in the cut area gets activated only when it comes in contact with air (oxygen actually) to form the clotting substance. The chemical for clotting of blood is released by the blood platelets.

Question 16.
What is translocation? How does it take place in plants?  [CBSE 2011]
Answer:
Translocation is the movement of materials from leaves to other tissues throughout the plant by the phloem. During translocation, sucrose is transferred into sieve tubes of phloem via the companion cells using energy from ATP. This increases the osmotic pressure inside the sieve tubes which causes movement of water into the sieve tubes from the adjacent xylem. This pressure helps in translocation of material in the phloem to tissues which have less pressure.

Question 17.
(a) Transport of food in plants require living tissues and energy. Justify this statement.
(b) Name the components of food that are transported by the living tissues.  [CBSE 2012]
Answer:
(a) The energy in the form of ATP is required both during loading of sucrose in the sieve tubes at the leaf surface and during uploading of the sucrose at the site which needs sucrose for its metabolic activities. So, it can be said that transport of food in plants require living tissues i.e., phloem and energy in the form of ATP.

(b) The components of food transported by the phloem are sugars, hormones, and minerals elements dissolved in water.

Question 18.
What are the adaptations of leaf for photosynthesis?  [NCERT Exemplar]
Answer:
The various adaptations in leaf for photosynthesis are:

• Leaves have expanded portion to provide large surface area for maximum light absorption.
• Leaves are arranged at right angles to the light source in a way that causes overlapping.
• The extensive network of veins helps in quick transport of substances in leaf.
• Easy gaseous exchange is facilitated by the presence of stomata on the leaves.
• The chloroplasts are more in number on the upper surface of leaves.

Question 19.
Why is small intestine in herbivores longer than in carnivores?  [NCERT Exemplar]
Answer:
Herbivores have a longer small intestine compared to the carnivores to allow time for the cellulose present in the grass to get digested. Cellulose takes longer time to get digested. Animals have shorter small intestine as they are not able to digest cellulose.

Question 20.
What will happen if mucus is not secreted by the gastric glands?  [NCERT Exemplar]
Answer:
Mucus forms the lining of the stomach and protects it from the action of hydrochloric acid released by the gastric glands of stomach. If mucus is not secreted then acidity and ulcers may be caused due to erosion of the inner lining of the stomach by the acid.

Question 21.
What is the significance of emulsification of fats?  [NCERT Exemplar]
Answer:
The large globules of fats are broken down into smaller fat globules by the action of bile salts present in the bile juice. This is called emulsification and it increases the efficiency of the fat digesting enzymes that can digest the smaller fat globules.

Question 22.
Why does absorption of digested food occur mainly in the small intestine?  [NCERT Exemplar]
Answer:
Maximum absorption occurs in small intestine because

• The process of digestion gets completed in the small intestine by intestinal juice.
• Finger-like projections called villi provide larger surface area for absorption.
• The villi are richly supplied with blood vessels to enable easy absorption into the bloodstream.

Question 23.

Answer:
(a) (iv)
(b) (iii)
(c) (i)
(d) (ii)

Question 24.
Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms?  [NCERT Exemplar]
Answer:
Aquatic animals use the oxygen dissolved in water. They breathe at a faster rate since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air.

Question 25.
In each of the following situations what happens to the rate of photosynthesis?  [NCERT Exemplar]
(a) Cloudy days
(b) No rainfall in the area
(c) Good manuring in the area
(d) Stomata get blocked due to dust
Answer:
(a) Decreases
(b) Decreases
(c) Increases
(d) Decreases

Question 26.
Name the energy currency in the living organisms. When and where is it produced?  [NCERT Exemplar]
Answer:
The energy currency in the cells is Adenosine triphosphate (ATP). It is produced in mitochondria during respiration and in chloroplasts during photosynthesis in plants.

Question 27.
What is common for Cuscuta, ticks and leeches?  [NCERT Exemplar]
Answer:
Cuscuta, ticks and leeches are parasites which obtain their nutrition from plants and animals without killing them.

Question 28.
Explain the role of mouth in digestion of food.  [NCERT Exemplar]
Answer:
The mouth plays an important role in digestion because

• The teeth present in the mouth crush the food into small pieces.
• Tongue helps in thorough mixing of food with saliva and to swallow the food.
• Saliva secreted in mouth contains an enzyme called salivary amylase which helps to break down the starch into maltose.

Question 29.
What are the functions of gastric glands present in the wall of the stomach?
Answer:
The functions of gastric glands present in the wall of the stomach are:

1. Produce pepsin enzyme that digests proteins.
2. Secrete mucus which protects the inner lining of stomach from the action of acids.

Extra Questions for Class 10 Science Chapter 6 Long Answer Type

Question 1.
How is oxygen and carbon dioxide transported in the human beings?  [CBSE All India 2008]
Answer:
At the alveolar surface, the oxygen diffuses out from the alveoli to the capillaries which surround the alveoli. The oxygenated blood is transported from the lungs to the heart which pumps it to the various parts of the body to supply it to various tissues.

At the tissue surface, the oxygen from the blood diffuses out into the tissues and carbon dioxide which is at higher concentration in the tissues, diffuses out into the capillaries. The capillaries transport the carbon dioxide rich blood from tissues to the alveoli where carbon dioxide diffuses out into the alveoli and oxygen enters into the capillaries to be transported to the tissues.

Question 2.
(a) State reason for the following:
(i) Herbivores need a longer small intestine while carnivores have shorter small intestine.
(ii) The lungs are designed in human beings to maximise the area for exchange of gases.
(b) The rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms.  [CBSE 2014]
Answer:
(a) (i) The cellulose present in the grasses takes a longer time to digest. So, the herbivores have a longer small intestine than the carnivores.
(ii) The alveoli present in the lungs provide a larger surface area for the exchange of gases in the lungs.

(b) Aquatic organisms breathe at a faster rate since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air.

Question 3.
Draw a diagram of excretory unit of human kidney and label the following:
(a) Bowman’s capsule
(b) Glomerulus
(c) Collecting duct
(d) Renal artery  [CBSE 2011, 2012]
Answer:

Question 4.
Explain how deoxygenated blood travels from body to lung for purification. Draw well labelled diagram in support of your answer.  [CBSE 2011]
Answer:
The deoxygenated blood from the various parts of the body is collected by the veins which transport the blood to the heart through the vena cava. Vena cava pours the deoxygenated blood in the right atrium of the heart. The right atrium contracts and the blood moves into the right ventricle. On contraction of the right ventricle the deoxygenated blood is transported to the lungs through the pulmonary artery for purification.

Schematic representation of transport and exchange of oxygen and carbon dioxide

Question 5.
Draw the sectional view of human heart and label the following parts given below:
(a) Chamber where oxygenated blood from lungs is collected
(b) Largest blood vessel in the body
(c) Muscular wall separating right and left chambers
(d) Blood vessel that carries blood from heart to the lungs  [CBSE 2010]
OR
(a) Part which receives deoxygenated blood from vena cava
(b) Part which sends deoxygenated blood to lung through pulmonary artery
(c) Part which receives oxygenated blood from lungs
(d) Part which sends oxygenated blood to all parts of the body through aorta  [CBSE 2012]
OR
(a) the chamber of heart that pumps out deoxygenated blood
(b) the blood vessel that carries away oxygenated blood from the heart
(c) the blood vessel that receives deoxygenated blood from the lower part of our body  [CBSE 2010, 2011, 2012]
Answer:

(а) Chamber where oxygenated blood from lungs is collected – Left atrium
(b) Largest blood vessel in the body – Aorta
(c) Muscular wall separating right and left chambers – Septum
(d) Blood vessel that carries blood from heart to the lungs – Pulmonary artery
OR
(а) Part which receives deoxygenated blood from vena cava – Right atrium
(b) Part which sends deoxygenated blood to lung through pulmonary artery – Right Ventricle
(c) Part which receives oxygenated blood from lungs – Left atrium
(d) Part which sends oxygenated blood to all parts of the body through aorta – Left Ventricle
OR
(а) the chamber of heart that pumps out deoxygenated blood – Right Ventricle
(b) the blood vessel that carries away oxygenated blood from the heart – Aorta
(c) the blood vessel that receives deoxygenated blood from the lower part of our body – Inferior Vena cava

Question 6.
Explain the process of nutrition in Amoeba.  [NCERT Exemplar]
Answer:
Nutrition in Amoeba:
Temporary finger-like extensions of the cell surface called pseudopodia are used by Amoeba to engulf food. Pseudopodia fuse over the food particle forming a food-vacuole in which complex substances are broken down into simpler ones and diffuse into the cytoplasm. The remaining undigested material moves to the surface of the cell and gets thrown out.

Question 7.
Describe the alimentary canal of man.  [NCERT Exemplar]
Answer:
Mouth: Helps in intake of whole food.
Teeth: Helps in chewing and grinding of food.
Tongue: Helps in tasting food + rolling food + swallowing food.

Salivary glands: Secrete saliva and mucus. The enzyme called salivary amylase is present in saliva which breaks down the complex starch into sugar.

Oesophagus (food pipe): Food moves towards stomach through oesophagus by rhythmic contraction of its muscles called as peristaltic movements or peristalsis.

Stomach: Muscular walls of stomach help in mixing food thoroughly with digestive juices. Stomach has gastric glands which secrete gastric juice containing pepsin for digestion of proteins, hydrochloric acid for creating acidic medium and mucus to protect inner lining of stomach from acid.

Small Intestine: Digestive juices like pancreatic juice, bile juice and the intestinal juices are secreted in the small intestine to help to complete the process of digestion. After digestion, the nutrients are absorbed by the villi present in the walls of the small intestine.

Large intestine: The unabsorbed food is sent into the large intestine where more villi absorb water from this material and remove the wastes through the anus by egestion. The exit of this waste material is regulated by the anal sphincter.

Question 8.
Explain the process of breathing in man.  [NCERT Exemplar]
Answer:
Air enters the body after getting filtered by fine hairs and mucus in the nostrils.
The air then passes through trachea (present in throat) into the lungs. The trachea divide into bronchi which enter the lungs and divide further into bronchioles which finally terminate in balloon-like structures called alveoli which have a rich supply of blood vessels and help in exchange of gases.

During inhalation (breathing in), the volume of the chest cavity becomes larger as the ribs get lifted and diaphragm gets flattened. Air gets sucked into the lungs and fills the expanded alveoli. The blood brings carbon dioxide from the rest of the body to the alveoli and exchanges it for oxygen to be transported to all the cells in the body.

During exhalation (breathing out), the volume of the chest cavity becomes smaller as the ribs get relaxed and diaphragm moves upward (relaxes). Air rich in carbon dioxide gets pushed out of the lungs to come out through the nostrils.

Question 9.
Explain the importance of soil for plant growth.
Answer:
Soil is important for the plant growth as it helps in the

• Anchoring the plant.
• Acts as a source of water and minerals for the plants.
• Ensures availability of oxygen for respiration of root cells.
• Microbes living in symbiotic association are found in the soil which helps to provide nitrogen for the plants.

Life Processes HOTS Questions With Answers

Question 1.
Which part of visible the spectrum is mostly ineffective in the process of photosynthesis? Why?
Answer:
The green part of the visible spectrum is mostly ineffective in the process of photosynthesis because chlorophyll involved in the process does not absorb green light. The green component of the visible spectrum gets reflected by the chlorophyll due to which the leaves appear green.

Question 2.
What difference would be seen in the small intestine of a grass eating animal and a flesh eating animal?
Answer:
The grass eating animal would have a longer small intestine than a flesh eating animal as the cellulose present in the grass takes a longer time to get digested.

Question 3.
The gall bladder of a patient is removed when a stone was observed in the gall bladder. Which kind of nutrient in the diet should be absent from the diet given to the patient?
Answer:
The gall bladder release bile juice which helps in the digestion of fats in the human beings. So, the patient should be advised a diet free from fats during the treatment process, as the digestion of fats will be most affected due to removal of gall bladder.

Question 4.
Stomata of desert plants remain closed during the daytime. Then how do they take up carbon dioxide and perform photosynthesis?  [CBSE 2010, 2012]
Answer:
The stomata of the desert plants open during the night time and absorb carbon dioxide to use it during the daytime for performing photosynthesis.

Question 5.
How do carbohydrates, proteins and fats get digested in human beings?
Answer:
An enzyme called salivary amylase is present in the saliva produced in the mouth. Salivary amylase helps in the breakdown of carbohydrates into maltose in the mouth.

The proteins get digested initially by the pepsin enzyme in the stomach and then by the enzymes present in the pancreatic juice secreted into the small intestine. The fats are broken down into small globules by the bile salts present in the bile juice secreted into the small intestine. This helps in increasing the efficiency of fat digesting enzymes.

The intestinal juice secreted by the walls of the small intestine help to complete the digestion of carbohydrates into glucose/monosaccharide, digestion of proteins into amino acids and the digestion of fats into fatty acids and glycerol.

Extra Questions for Class 10 Science Chapter 6 Value Based Questions

Question 1.
Raksha planted many plants in her home garden as she knew that the plants help to purify air. To get purified air in her room she kept some of the plants in a closed room, it leaves turned pale in colour after some days.
(a) Define photosynthesis. What are the conditions necessary for photosynthesis?
(b) What are the values shown by Raksha?
(c) What can be the most probable reason which resulted in the pale leaves?
Answer:
(a) The process by which the autotrophs synthesise their own food is called as photosynthesis.
Photosynthesis,occurs in the presence of carbon dioxide, water, chlorophyll and sunlight.
(b) The values shown by Raksha are intelligence, environment friendly, scientific temper, creative thinking.

Question 2.
Ayush experienced muscular cramps during the training session for his upcoming cricket match. His coach advised him a schedule of aerobic exercises to overcome this problem. Ayush followed his coach’s advice and did not experience any muscular cramps during the game. Based on this, answer the following questions:
(а) What was the reason for the muscular cramps?
(b) What was the effect of aerobic exercises?
(c) What are the values shown by Ayush?
Answer:
(a) The muscular cramps were caused as the muscles produced lactic acid during anaerobic respiration in the muscle cells. The accumulation of lactic acid caused the cramps.

(b) Aerobic exercises helped in providing enough oxygen for the various muscle cells so that they had a more supply of oxygen.

(c) Values shown by Ayush are respect for his coach, responsibility, hard work and patience.

Question 3.
Anshika noticed that one of the plants in her garden had wrinkled and drooping leaves. She went to the garden and felt the soil below the plant which was too dry. She immediately made provisions for watering the plant and made a daily schedule for watering it every day. Within a few days the plant revived and became green and healthy. On the basis of this text, answer the following questions:
(a) How is water transported up into the plants?
(b) What is the role of the leaves and the roots in such transport?
(c) What are the values shown by Anshika?
Answer:
(a) Water is transported up into the plants with the help of xylem. The movement of water in the xylem occurs due to transpiration and root pressure.

(b) Roots absorb water through their root hairs. Leaves have stomata through which transpiration occurs and pulls up the water through the xylem to the top of the plant.

(c) The values shown by Anshika are: Love for nature, scientific aptitude, awareness, care

Question 4.
Sameer went to a forest and observed the villagers collecting reins and gums from the plants. He asked the villagers about the use of the resins and gums. They told him that they will be used in making the paints and varnishes for furniture. He learnt the technique of collecting resins from the villagers and enjoyed the activity with the villagers by helping them in collection.
On the basis of the text, answer the following questions:
(а) Why are resins and gums released by plants?
(b) What are the ways in which plants get rid of their waste products?
(c) What are the values shown by Sameer?
Answer:
(a) Resins and gums are the excretory products of the plants.
(b) Plants remove excess oxygen and carbon dioxide through stomata, excess water by transpiration through stomata and other waste products by storage in cellular vacuoles, leaves that fall off, storage as resins and gums in old xylem or by excreting into the soil around them.
(c) Values shown by Sameer are: Care of the environment, scientific attitude, helpfulness, curiosity.

In this page, we are providing Control and Coordination Class 10 Extra Questions and Answers Science Chapter 7 pdf download. NCERT Extra Questions for Class 10 Science Chapter 7 Control and Coordination with Answers will help to score more marks in your CBSE Board Exams.

Class 10 Science Chapter 7 Extra Questions and Answers Control and Coordination

Extra Questions for Class 10 Science Chapter 7 Control and Coordination with Answers Solutions

Extra Questions for Class 10 Science Chapter 7 Very Short Answer Type

Question 1.
Define ‘reflex action’.  [CBSE 2009]
Answer:
It is an automatic, spontaneous and an immediate involuntary response to a stimulus controlled usually by the spinal cord. e.g. knee jerk movement.

Question 2.
Name the largest cell in the human body.  [CBSE 2003]
Answer:
Nerve cell (Neuron).

Question 3.
Give an example of plant hormone that promotes growth.  [CBSE 2008]
Answer:
Auxin

Question 4.
What are plant hormones?  [CBSE 2008]
Answer:
The chemical substances produced in plants which help in the growth and development of plant, its tissues and other plants.

Question 5.
Name the part of neuron   [CBSE 2008]
(а) where information is acquired.
(b) through which information travels an electrical impulse.
Answer:
(a) Dendrite
(b) Axon

Question 6.
Name two tissues that provide control and coordination in multicellular animals.  [CBSE 2009]
Answer:
Muscular tissues and nervous tissue.

Question 7.
Name the hormone, the secretion of which is responsible for dramatic changes in appearance in girls and boys when they approach 10-12 years of age.   [CBSE 2008]
Answer:
Testosterone released from testes in males, estrogen released from ovaries in females.

Question 8.
Name the hormone that helps in regulating level of sugar in our blood. Name the glands that secretes it. [CBSE 2010]
Answer:
Insulin hormone secreted by pancreas.

Question 9.
Name a plant hormone that inhibits growth. Write its one more function.  [CBSE 2014]
Answer:
Abscisic acid inhibits growth in plants. It also causes closure of stomata during water stress.

Question 10.
A potted plant is made to lie horizontally on the ground. Which part of the plant will show:
(i) Positive geotropism
(ii) Negative geotropism  [CBSE 2010]
Answer:
(i) Roots will shows positive geotropism.
(ii) Shoots will show negative geotropism.

Question 11.
Name a plant hormone which promotes growth in plants.  [CBSE 2008]
Answer:
Auxin is a plant hormone that promotes growth and cell elongation in plants.

Question 12.
State one function each of pons and cerebellum.
Answer:
Pons: Regulates rate of respiration
Cerebellum: Maintains equilibrium of the body during walking, jumping, etc.

Question 13.
Name a gaseous plant hormone. Give its role.
Answer:
Ethylene is a gaseous hormone. It regulates fruit ripening.

Question 14.
How many spinal and cranial nerves are present in human body?
Answer:
Spinal nerves = 31 pairs
Cranial nerves = 12 pairs

Question 15.
What are meninges?
Answer:
The three membranes which cover the brain to protect it are called meninges.

Extra Questions for Class 10 Science Chapter 7 Short Answer Type I

Question 1.
How do we detect smell of hot spicy food from a distance?
Answer:
We have olfactory receptors in our nose which detect the smell of hot spicy food.
This information is transmitted by nerve impulse to olfactory lobes of forebrain which interpret the information.

Question 2.
Why do tendrils coil around hard objects or support?
Answer:
The tendrils coil around hard objects or support due to a stimulus of touch (thigmotropism) which causes less growth on the side in contact with support than the side which is away from it. This unequal growth of two sides of tendril makes it coil around the support.

Question 3.
Name the hormones reponsible for regulation.
(i) Metabolism of carbohydrates, fats and proteins
(ii) Balance of calcium and phosphate
(iii) Blood pressure
(iv) Water and electrolyte balance.  [CBSE 2007]
Answer:
(i) Thyroxin
(ii) Parathyroid hormone
(iii) Adrenaline
(iv) Vasopressin

Question 4.
What is an association neuron?
Answer:
Association neurons are present in cortex part of spinal cord between the sensory neuron and motor neuron. It helps to interconnect the signals between the sensory neuron and motor neuron by forming synapse with axon of sensory neuron and dendrite of motor neuron.

Question 5.
How are the brain and spinal cord protected from mechanical shock?
Answer:
Brain is present in a bony box called cranium (skull), spinal cord is protected by vertebral column. The cerebrospinal fluid present around the brain and spinal cord protect it from mechanical shock.

Question 6.
Which functions are regulated by the forebrain?
Answer:
The thinking part of the brain is forebrain which controls

• Movement of voluntary muscles.
• Hearing, smell, sight, hunger, thirst, pain, etc. by its association areas.
• It also stores information and controls intelligence.

Question 7.
Explain how a squirrel responds a dangerous situation with help of its hormonal system.
Answer:
When a squirrel perceives a dangerous situation, adrenaline hormone is released in its blood which increases its heart beat and blood supply to tissues. This provides energy to its cells and tissues at a faster rate and enables it to run away from emergency situation.

Question 8.
How are sensory neurons different from motor neurons?
Answer:
Sensory neuorons take information from receptors and transmit the impulses towards central nervous system. Motor neurons carry message from control nervous system to the muscle, gland or an organ to enable it to respond.

Question 9.
How are receptors different from effectors?
Answer:
Receptors are cells, tissues or organs which receive the information in form of stimulus. For example, photoreception, gustatory receptors, etc. Effectors are muscles, glands tissues or cells which respond according to the information received through motor neuron from the central nervous system.

Question 10.
Define peripheral nervous system. What are its components?
Answer:
The nerves that directly arise from the central nervous system and contact different parts of our body to help their involuntary controls. Spinal nerves and cranial nerves are components of peripheral nervous system.

Question 11.
Lable the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in the given figure.

Answer:
(a) Sensory neuron
(b) Spinal cord (part of CNS)
(c) Motor neuron
(d) Effector (Muscle)

Question 12.
Name the plant hormones responsible for the following:
(a) elongation of cells
(b) growth of stem
(c) promotion of cell division
(d) falling of senescent leaves
Answer:
(a) Auxin
(b) Gibberellin
(c) Cytokinin
(d) Abscissic acid

Question 13.
Label the endocrine glands in figure given below.

Answer:
(a) Pineal Gland
(b) Pituitary Gland
(c) Thyroid
(d) Thymus

Question 14.
Label the parts of a neuron in figure given below.

Answer:
(a) Dendrite
(b) Cell Body
(c) Axon
(d) Nerve ending

Question 15.
Match the terms of Column (A) with those of Column (B)

[NCERT Exemplar]
Answer:
(a) (iii)
(b) (iv)
(c) (i)
(d) (ii)

Extra Questions for Class 10 Science Chapter 7 Short Answer Type II

Question 1.
What are nastic and curvature movements? Give one example of each.  [CBSE 2010]
Answer:
The non-directional responses to stimuli are called nastic movements e.g., drooping of leaves of touch-me-not plant. Curvature movement are the movement of plant parts towards or away from stimulus e.g., bending of shoot towards light.

Question 2.
How does feedback mechanism regulate the hormone action? Explain with the help of an example.
Answer:
The presence or absence of a particular hormone can regulate its further formation with the help of a regulatory mechanism called feedback mechanism.

Example: Hypothalamus regulates thyroxin levels in blood by secreting thyroid stimulating hormone (TSH). If the thyroxine levels increases then hypothalamus stop secreting TSH in order to reduce the production of thyroxine from thyroid gland.

Low levels of thyroxin in blood again switches on the release of TSH from hypothalamus to increase levels of thyroxin in blood.

Question 3.
What are the different types of neurons and their functions in the human body?
Answer:
There are mainly three types of neurons:

1. Sensory neuron: They transmit information from receptors towards the central nervous system.
2. Motor neuron: They transmit information from the central nervous system to effectors like muscles or glands.
3. Relay neuron: It serves as a link between the sensory and the motor neurons in the brain or spinal cord.

Question 4.
What are the limitations to the use of electrical impulse?
Answer:
The limitations to electrical impulse are

1. Only those cells used that are connected by nervous tissue, while other tissues do not receive the information directly.
2. It takes some times to reset the mechanism of generation of new electrical impulse once an electrical impulse had been generated.

Question 5.
Depict the mechanism of Nervous tissue action.
Answer:
The mechanism of nervous tissue action is:

Question 6.
What is a tropic movement? Explain with an example. [NCERT Exemplar]
Answer:
The directional movements caused in plants due to an external stimuli are called tropic movements.
Example: During phototropism, the shoot bends towards light and show positive phototropism while the roots bend away from light to show negative phototropism.

Question 7.
What will happen if intake of iodine in our diet is low?  [NCERT Exemplar]
Answer:
Iodine helps in the synthesis of thyroxin hormone from thyroid gland. Thyroxin hormone is necessary for carbohydrate, proteins and fat metabolism.
Deficiency caused due to low level of iodine in diet might result is a disease called goitre in the person.

Question 8.
Answer the following:
(a) Which hormone is responsible for the changes noticed in females at puberty?
(b) Dwarfism results due to deficiency of which hormone?
(c) Blood sugar level rises due to deficiency of which hormone?
(d) Iodine is necessary for the synthesis of which hormone?  [NCERT Exemplar]
Answer:
(a) Oestrogen
(b) Growth hormone
(c) Insulin
(d) Thyroxin

Question 9.
Answer the following:
(a) Name the endocrine gland associated with brain.
(b) Which gland secretes digestive enzymes as well as hormones?
(c) Name the endocrine gland associated with kidneys.
(d) Which endocrine gland is present in males but not in females?  [NCERT Exemplar]
Answer:
(a) Pituitary
(b) Pancreas
(c) Adrenal gland
(d) Testes

Extra Questions for Class 10 Science Chapter 7 Long Answer Type

Question 1.
Differentiate between tropic and nastic movements in plants.  [CBSE 2006]
Answer:
Tropic Movements:

1. There is directional growth of a plant or part of a plant in response to an external stimulus i.e., direction of stimulus controls direction of growth.
2. The effect is more or less permanent.
3. It is easily observed in stems and roots of plants.
4. It occurs due to unequal growth on the two sides of a stem or root.
5. For example, bending of root towards gravity and bending of shoot towards light.

Nastic Movements:

1. The growth or movement is independent of the direction of stimulus.
2. The effect is temporary and reversible.
3. It occurs in specialised parts and organs of plants like leaves and petals of flowers.
4. It usually involves alterations in cell volumes.
5. For example, folding on leaflets of touch-me-not plant on touching them.

Question 2.
Mention one function for each of these hormones:
(a) Thyroxin
(b) Insulin
(c) Adrenaline
(d) Growth hormone
(e) Testosterone
Answer:
(a) Thyroxin: It regulates carbohydrates, fat and protein metabolism.
(b) Insulin: It regulates blood sugar level.
(c) Adrenaline: It increases heart beat rate and supply of blood to various organs.
(d) Growth hormones: It regulates growth and development of an organism.
(e) Testosterone: It controls the bodily features, secondary sexual characters in males during puberty.

Question 3.
How does chemical coordination take place in animals?
Answer:
Hormones secreted by the endocrine glands are directly poured into the blood stream as they are ductless glands. Blood carries these hormones to specific target tissue or organ where they act and trigger a particular biochemical or physiological activity in response to the stimulus received.

Question 4.
Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the reverse?  [NCERT Exemplar]
Answer:
The information received by the dendrites of neurons present at receptors is transferred in form of electrical impulse to the cell body, axon and the nerve endings at the ends of axon. At the axonal ends, chemicals are released between junction of two neurons called synapse. The chemical diffuses towards the dendrite of the next neuron where it generates an electrical impulse again. So, the electrical signals change to chemical signals and again to electrical signals for the next neuron.

Since the chemicals Eire released at the axonal ends and absent at dendrite end, the signal travels from axonal end to dendritic end of another neuron but not the reverse i.e., the flow of electrical impulse is unidirectional only.

Control and Coordination HOTS Questions With Answers

Question 1.
While most of our actions are coordinated by the brain, still some of our actions need to be coordinated by the spinal cord. Why?
Answer:
Brain is the thinking part which coordinates the various activities and processes in human beings. But, some actions which need to be quick, automatic and involuntary, do not involve any thinking processes.
So, such immediate responses are coordinated by the spinal cord and are called reflex actions.

Question 2.
The movements shown by the leaves of ‘touch me not’ plant on touching are different from the movement shown by seedling. Elaborate.
Answer:
The opening and closing of the leaves of the ‘touch me not plant’ is a result of water change in amount of water in the plant cells, which is not dependent on growth. But, the movement of the seedling is a growth-dependent movement because it will not show any movement if it is prevented from growth.

Question 3.
The level of hormones should be well balanced in human beings in order to maintain the normal functioning of the human body. Explain this statement with two examples.
Answer:
The level of hormones should be balanced in human beings because a deficiency or excess secretion of some hormones can have adverse effects on the human body. For example,

• A deficiency in the secretion of insulin from the pancreas increases the blood sugar level and causes diabetes.
• A deficiency in the secretion of growth hormone causes dwarfism whereas it excess secretion causes gigantism.

Question 4.
Chemical coordination plays a vital role in the activities of plants. Elaborate.
Answer:
Coordination in human beings is carried out both by the nervous as well as the hormonal system. But, coordination in plants is dependent on the chemicals called as hormones. The hormone auxin and gibberellins help in the growth of the stem. Cytokinins help in cell division. Abscisic acid inhibits growth. Auxin is also involved in the bending of plants towards light.

Question 5.
The response of the body due to reflex actions is faster than those carried out by secretion of adrenaline in emergency situations. Why?
Answer:
The reflex actions are the result of chemical-electrical impulses which are faster as they move through the nerve cell from one point to another, whereas, hormones are first released in the blood and they have to travel to the target site to bring about the response, which takes more time than reflex actions.

Extra Questions for Class 10 Science Chapter 7 Value Based Questions

Question 1.
Villagers living in a hilly area were facing a problem that a lot of children in the village were developing swollen necks. The priest of the village told that it was due to the acts of the villagers who had annoyed their Goddess and they needed to offer sacrifice for getting rid of this problem. Dr. Kamal visited the village and properly listened to the problem of the villagers and advised them to use iodised salt instead of normal salt in their food. Villagers agreed to Dr. Kamal’s advice and within a few months the problem was overcome to a large extent.
(a) What was the cause of the swollen neck of children in the village?
(b) What values are shown by Dr. Kamal?
(c) Why was use of iodised salt advised to villagers by Dr. Kamal?
Answer:
(a) The swollen neck is a disease called goitre. Goitre occurs due to deficiency of thyroxine hormone.
(b) Scientific aptitude, patience, problem solving ability and helpful nature.
(c) The use of iodised salt was advised because Iodine helps in production of thyroxine hormone which helps to prevent goitre.

Question 2.
Akhilesh saw a plant in his school garden which closed its leaves on touching. He observed the plant very closely for a long time. In the recess, he saw that some students were trying to pluck the plant from the pot. He went to them and advised them not to pluck the plant as it was their school’s property. He also told them about the importance of the plants and the peculiar behavior of the said plant. In this way, he was able to convince the students to not harm the plant.
(a) Why did the leaves of the plant close on touching?
(b) How is this response of plant different from reflex action in animals?
(c) What values are shown by Akhilesh?
Answer:
(a) The leaves of the sensitive plants like Touch-me-not close on touching as they lose the turgor pressure in cells which causes drooping of its leaves/leaflets.

(b)
Movement in Sensitive Plant:

1. The response is produced due to the change in amount of water in the plant cells.
2. No nerve or specialised tissue involved in the conduction of information.

Reflex action:

1. An automatic, immediate, involuntary response of an organism.
2. It is controlled by the spinal cord.

(c) Environment friendly, responsible, leadership, analytical thinking.

Question 3.
Smita’s father was complaining about frequent urination, pain in legs and a frequent weight loss to Smita’s mother and she discussed the things with her daughter when Smita returned from school. Listening to this Smita told her mother that her father should go and visit a doctor immediately. The doctor diagnosed that Smita’s father was having an elevated level of blood glucose. He should take care of his diet and should exercise regularly to maintain his normal glucose level.
On the basis of the text, answer the following questions:
(i) Name the disease he is suffering from and name the hormone whose deficiency causes it.
(ii) Identify the gland that secretes it and mention the function of this hormone.
(iii) Explain how the time and amount of secretion of this hormone is regulated in human system.
(iv) What values were shown by Smita and her father? [CBSE 2012, 2015]
Answer:
(i) Disease-Diabetes, Hormone: Insulin (deficiency of insulin hormone causes diabetes)
(ii) Gland-Pancreas: The blood glucose level is regulated by insulin hormone secreted by the pancreas.
(iii) Cells of pancreas secrete insulin hormone when level of blood glucose level increases in the blood. Insulin regulates the blood glucose level and its secretion gets reduced when blood glucose level falls down.
(iv) Decision making, intelligence, scientific aptitude and caring nature is shown by Smita. Her father had shown an attitude of carelessness towards his health.

Question 4.
Rajesh found an old man lying on the road asking for help to take him to the hospital. He took the old man to the hospital where doctor told him that the old man was suffering from paralysis, and his blood sugar levels were high. The doctor told him that they have given the old man some injections to reduce the blood sugar level and thanked Rajesh for his helpful attitude.
On the basis of above passage, answer the following:
(i) What can be the cause of high blood sugar levels in the old man?
(ii) Which part of old man’s body might have been effected that has caused paralysis?
(iii) What values have been shown by Rajesh?
(iv) Which injection might have been given to old man by doctor to lower the blood sugar levels?
Answer:
(i) Diabetes due to the lower levels of insulin hormone in the body.
(ii) Nervous system associated with brain or spinal cord might have been effected.
(iii) Helpful, care for elderly.
(iv) Injections of insulin might have been given by the doctor to the old man to lower his blood sugar levels.

In this page, we are providing Periodic Classification of Elements Class 10 Extra Questions and Answers Science Chapter 5 pdf download. NCERT Extra Questions for Class 10 Science Chapter 5 Periodic Classification of Elements with Answers will help to score more marks in your CBSE Board Exams.

Class 10 Science Chapter 5 Extra Questions and Answers Periodic Classification of Elements

Extra Questions for Class 10 Science Chapter 5 Periodic Classification of Elements with Answers Solutions

Extra Questions for Class 10 Science Chapter 5 Very Short Answer Type

Question 1.
Name two elements whose properties were predicted on the basis of their positions in Mendeleev’s periodic table.
Answer:
Gallium (Eka-aluminium) and germanium (Eka-silicon).

Question 2.
Write the formulae of chlorides of Eka-silicon and Eka-aluminium, the elements predicted by Mendeleev.  [NCERT Exemplar]
Answer:
Eka-aluminium represents gallium (Ga) with valency three and Eka-silicon is for germanium (Ge) with valency four. The formulae of their respective chlorides are GaCl₃ and GeCl₄.

Question 3.
How many elements are there in period 2?
Answer:
Eight (8).

Question 4.
Name all the elements present in group-17 of the Modern Periodic Table.
Answer:
F, Cl, Br, I, At.

Question 5.
Name two elements whose atomic weight were corrected on the basis of their position in Mendeleev’s periodic table.
Answer:
Gold (Au) and platinum (Pt).

Question 6.
Arrange the following elements in the increasing order of their metallic character.
Mg, Ca, K, Ge, Ga     [NCERT Exemplar]
Answer:
Ge < Ga Mg < Ca < K.

Question 7.
Name the scientist who proposed the Modern Periodic Law.
Answer:
Henry Moseley, a scientist, proposed the Modern Periodic Law.

Question 8.
What is meant by a group in the periodic table?
Answer:
Groups are the vertical columns/vertical lines in the periodic table.

Question 9.
What is meant by a period in the periodic table?
Answer:
Periods are the horizontal rows in the periodic table.

Question 10.
Name the elements present in period 1 of the modern periodic table.
Answer:
Hydrogen (H) and Helium (He).

Question 11.
An element A is in group II (group 2) of the periodic table:
(а) What will be the formula of its chloride?
(b) What will be the formula of its oxide?
Answer:
(a) ACl₂
(b) AO.

Question 12.
Why are the elements calcium, strontium and barium named as alkaline earths?
Answer:
These elements are called alkaline earths because their oxides are alkaline in nature and exist in the earth.

Question 13.
Give the name and electronic configuration of second alkali metal.
Answer:
The second alkali metal is sodium (Na). Its electronic configuration is 2, 8, 1.

Question 14.
What are Metalloids?
Answer:
Those elements which show some properties of both metals and non-metals are called metalloids. Examples: Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium and Polonium.

Question 15.
Name three elements whose atomic masses were correct on the basis of their positions in Mendeleev’s periodic table.
Answer:

1. Beryllium (Be, group II A)
2. gold (Au, group II B)
3. platinum (Pt, group VIII).

Question 16.
Name three elements which behave as metalloids.
Answer:
The elements are:

1. arsenic (As)
2. antimony (Sb)
3. germanium (Ge).

Question 17.
Name the inert gas which has two electrons in its valence shell.
Answer:
Helium.

Question 18.
Name the most metallic and most non-metallic element in the Periodic Table.
Answer:
The most metallic elements is francium (group 1) and most non-metallic element is fluorine (group 17).

Question 19.
In the Modern Periodic Table, which are the metals among the first ten elements?
Answer:
Lithium (Li), Beryllium (Be) and Boron (B) are the metal elements among first ten elements in the Modern Periodic Table.

Question 20.
Two elements A and B belong to the same period. What is common in them?
Answer:
They have the same number of shells.

Question 21.
The electronic configuration of an element is 2, 8, 6. Identify the element and name of the family to which it belongs.
Answer:
The element with configuration 2, 8, 6 (Z = 16) is sulphur. It belongs to the oxygen family.

Question 22.
Calcium, Strontium and Barium form a Dobereiner’s triad. The atomic masses of calcium and Barium are 40 and 137 respectively. Predict the atomic mass of strontium.
Answer:
According to Dobereiner’s triad, atomic mass of strontium is the arithmetic means of Ca and Ba as strontium lies between Ca and Ba.
Atomic mass of Sr = \(\frac{40+137}{2}=\frac{177}{2}=88.5\)

Question 23.
The formula of magnesium oxides is MgO. Write the formula of magnesium chloride.
Answer:
Oxygen is divalent in nature. The valency of magnesium in magnesium oxide is + 2. The formula of magnesium chloride is MgCl₂ since chlorine has valency equal to one.

Question 24.
State whether the following statement is true or false?
The valency of an element of group 17 is 7.
Answer:
This statement is wrong. The number of valence electrons in an element of group 17 = 17 – 10 = 7.
Therefore, the valency of the element = 8 – 7 = 1.

Question 25.
Name two elements whose atomic weight were corrected on the basis of their position in Mendeleev periodic table.
Answer:

1. Gold (Au)
2. Platinum (Pt).

Question 26.
The two isotopes of chlorine have atomic mass 35.4 and 37.4. Should they be placed in separate slots in the modern periodic table?
Answer:
No, they should be placed in the same slot because the modern periodic table is based on the atomic number of the elements.

Question 27.
List any two properties of the elements belonging to the first group of the modem periodic table.   [Delhi 2014]
Answer:
Elements of first group have one valence electron each in their atoms. All the elements of group 1 have the same valency of 1.

Question 28.
What is the basic difference in the electronic configuration of the elements belonging to group 1 and group 2?
Answer:
All elements belonging to group 1 have one electron in the valence shell while all elements belonging to group 2 have two electrons in their valence shell.

Question 29.
Element ‘Y’ with atomic number 3 combines with element ‘A’ with atomic number 17. What will be the formula of the compound?
Answer:
The electronic distribution in elements ‘A’ and ‘Y’ are 2, 1 and 2, 8, 7 respectively. Both have valency equal to 1. The formula of the compound is AY.

Question 30.
Name the property which remains unchanged on descending a group in the periodic table.
Answer:
Valence electrons.

Question 31.
An element X is in group 13 of the periodic table. What is the formula of its oxide?
Answer:
X₂O₃.

Question 32.
Elements ‘X’ and TP belong to groups 1 and 17 of the periodic table respectively. What will be the nature of the bond in the compound XY?
Answer:
Ionic bond.

Extra Questions for Class 10 Science Chapter 5 Short Answer Type I

Question 1.
The three elements A, B and C with similar properties have atomic masses X, Y and Z respectively. The mass of Y is approximately equal to the average mass of X and Z. What is such an arrangement of elements called? Give one example of such a set of elements.   [NCERT Exemplar]
Answer:
The arrangement of these elements is known as Dobereiner triad. Example, Lithium, sodium and Potassium.

Question 2.
In group I of the periodic table, three elements X, Y and Z have atomic radii 1.33 A, 0.95 A and 0.60 A respectively. Arrange the elements (X, Y and Z) in the increasing order of atomic number and mention a suitable reason for it.
Answer:
In a given group, the atomic radii increases on moving down the group. Therefore, the arrangement of the given elements in the increasing order of their atomic numbers is as follows: Z, Y, X.

Question 3.
Elements have been arranged in the following sequence on the basis of their increasing atomic masses.
F, Na, Mg, Al, Si, P, S, Cl, Ar, K
(a) Pick two sets of elements which have similar properties.
(b) The given sequence represents which law of classification of elements?   [NCERT Exemplar]
Answer:
(a) F and Cl are first and eighth element in the above sequence, therefore, they have similar properties.
Please note that although Na and K have similar properties but they are not related as first and eighth element in the above sequence.

(b) This sequence represents Newland’s Law of Octaves.

Question 4.
State and explain Mendeleev’s periodic law.
Answer:
According to Mendeleev’s periodic law “Physical and chemical properties of elements are periodic function of their atomic masses”.

If elements are arranged in the increasing order of atomic masses, elements with similar properties lies after a certain interval in the periodic table.

Question 5.
“Hydrogen occupies a unique position in the Modern Periodic Table”. Justify the statement.   [NCERT Exemplar]
Answer:
The position of the element hydrogen is still not clear even in the Modern Periodic Table.

In electronic configuration, it resembles alkali metals of group 1. All of them have only one electron in the valence shell. Actually, hydrogen has only one shell (K-shell) which has one electron.

In characteristics, it resembles halogens of group 17. For example, like halogens hydrogen is a non-metal and diatomic as well. It has been therefore, decided to assign hydrogen a unique position in the Modern or Long Form Periodic Table. It is placed at the top in group 1 of alkali metals. However, it is not a member of that group.

Question 6.
If an element X is placed in group 14, what will be the formula and the nature of bonding of its chloride?  [NCERT Exemplar]
Answer:
Since element “X’ is placed in group 14, therefore, its valency is 14 – 10 = 4. Further, since it is difficult to either lose all the four valence electrons or gain four more electrons, therefore, it prefers to share these four electrons to acquire the stable electronic configuration of the nearest inert gas. Its formula will be XCl₄. Thus, the nature of the chloride of element ‘X’ is covalent.

Question 7.
Explain clearly, why atomic number of an element is most important to the chemist than its relative atomic mass.
Answer:
Atomic number corresponds to the number of electron in an atom or it reflects the electronic configuration of the element. The elements having similar electronic configurations can then be placed together in the same group, it helps in the systematic classification of elements.

On the other hand, the atomic mass of an element does not provide the electronic configuration of an element, so atomic number is more fundamental property for classification of elements.

Question 8.
What is the need of classification of the elements?
Answer:
The following reasons can be assigned for practical utility of classification of elements:

• To make the study of chemical elements easier.
• To correct atomic masses of various elements.
• To discover new elements.

Question 9.
The elements calcium, strontium and barium were put in one group or family on the basis of their similar properties.
(i) Mention the two similar properties?
(ii) What is the usual name of this group or family?
Answer:
(i) (a) All these elements are metals.
(b) All these elements have a valency of 2.

(ii) The usual name of this group or family is alkaline earth metals.

Question 10.
How does the electronic configuration of an atom of an element relate to its position in the modem periodic table? Explain with one example.   [CBSE 2011 (Delhi)]
Answer:
The electronic configuration of an atom of an element gives its position in the modern periodic table.
(i) The ‘period number’ of an element is equal to the number of electron shells in its atom.
(ii)

• The group number of an element having upto two valence electrons is equal to the number of valence electrons.
• The group number of an element having more than 2 valence electrons is equal to the number of valence electrons plus 10.

Example: If the electronic configuration of an element is 2, 8, 7.
Then its period number is 3 as it has three electrons shells.
Its group number is 17 as it has 7 valence electrons. (∵ Group no. = 7 + 10 = 17)

Question 11.
An element X (atomic number 17) combines with an element Y (atomic number 20) to form a compound.
(i) Write the positions of these elements in the modern periodic table.
(ii) Write the formula of the compound formed. Justify your answer in each case.   [CBSE 2013]
Answer:
(i) The electronic configurations of the two elements are:
X (Z = 17) 2, 8, 7 ; Y (Z = 20) 2, 8, 8, 2.
Element X is present in group 17 (halogen family) since it has 7 valence electrons. Element Y is placed in group 2 (alkaline earth family) since it has 2 valence electrons.

(ii) Element Y is a metal with valency 2 while element X is a non-metal with valency 1. Therefore, they two combine to form compound YX₂.

Question 12.
Explain why:
(i) All the elements in a group have similar chemical properties.
(ii) All the elements in a period have different chemical properties.
Answer:
(i) All the elements in a particular group have similar outer shell electronic configuration. Since chemical properties of an element are determined mainly by the outer shell configuration, all the elements in a group have similar chemical properties.

(ii) All the elements in a period have different valence shell electronic configuration because they have different number of electrons in the valence shell. Hence, the elements in a period have different chemical properties.

Question 13.
Given below are the atomic radii of three elements X, Y and Z of the periodic table, each having n electrons in the outermost shell of their atoms:

Answer the following:
(a) Do these elements X, Y and Z belong to same group or to the same period?
(b) Which element will be least metallic?
Answer:
(a) Since the elements X, Y and Z contain same number of electrons (n) in the valence shell (outermost shell), they belong to the same group.
(b) In a group, the atomic radius increases on descending the group. Therefore, the element X with the smallest atomic radius is at the top of the group and the element Z having largest atomic radius is at the bottom.

Now, we know metallic character increases as we move from top to bottom in a group. Therefore, the least metallic element is X.

Question 14.
(a) The elements of the second period along with their atomic numbers in parentheses are given below:
B (5), Be (4), O (8), N (7), Li (3), C (6), F (9)
(i) Arrange them in the same order as they appear in the periodic table.
(ii) Which element has the largest and smallest atom?
(b) Why does atomic radius change as we move from left to right in a period?   [CBSE 2011]
Answer:
(a) (i) Li (3), Be (4), B (5), C (6), N (7), O (8), F (9)
(ii) The element Li has the largest atom. The element F has the smallest atom.

(b) Along a period, the nuclear charge increases and the electrons are attracted more towards the nucleus. Therefore, the atomic size or atomic radius decreases as we move from left to the right along a period.

Question 15.
Write two reasons responsible for the late discovery of noble gases.   [CBSE 2013]
Answer:

1. Noble gas elements were not present in earth crust as minerals like other elements and were present in air to a very small extent.
2. Their atoms have stable electronic configuration of their outermost shells also called valence shells. (2 in case of He and 8 for other elements). They do not combine with atoms of other elements.

That is why, noble gas elements were discovered at a later stage.

Question 16.
From the following elements:
₄Be; ₉F; ₁₉K; ₂₀Ca
(i) Select the element having one electron in the outermost shell.
(ii) two elements of the same group.
Write the formula of and mention the nature of the compound formed by the union of ₁₉K and element X (2, 8, 7). [Delhi 2015]
Answer:
(i) ₁₉K
(ii) ₄Be, ₂₀Ca belong to the same group.
Electronic configuration of K (19) = 2, 8, 8, 1   Valency of K = 1
Electronic configuration of X (2, 8, 7)   Valency of X = 1

The formula of the compound formed is KX. The compound KX is of ionic nature.
The bond is formed by transference of electrons.

Question 17.
Na, Mg and Al are the elements of the same period of Modern Periodic Table having one, two and three valence electrons respectively. Which of these elements (i) has the largest atomic radius, (ii) is least reactive? Justify your answer stating reason for each case.   [Delhi 2015]
Answer:

(1) Na has the largest atomic radius because on moving from left to right in the periodic table, the atomic radius decreases due to increase in positive charge on the nucleus which pulls the outermost electrons more close to the nucleus and the size of atom decreases.

(2) Al is least reactive because on moving from left to right in the periodic table the nuclear charge increases and the valence electrons are pulled in more close to the nucleus. Therefore, the tendency to lose electrons decreases and hence reactivity decreases.

Question 18.
How many groups and periods are there in the modern periodic table? How do the atomic size and metallic character of elements vary as we move: (a) down a group and (b) from left to right in a period. [Delhi 2015]
Answer:
Number of groups is 18 and number of periods in the modern periodic table is 7.
(a) All the elements in a group have the same valency. On going down in a group, the atomic size increases because a new shell of electrons is added to the atoms at every step.

(b) On moving from left to right in the periodic table, the valency of the elements first increases from 1 to 4 and then decreases to zero. On moving from left to right in a period, the metallic character of elements decrease because on moving from left to right in a period, the electropositive character of elements decrease.

Question 19.
The electronic configuration of an element X is:

(i) What is the group number of element X in the periodic table?
(ii) What is the period number of element X in the periodic table?
(iii) What is the number of valence electrons in an atom of X?
(iv) What is the valency of X?
Answer:
(i) From the above given electronic configuration we find that element X has 6 valence electrons in the outermost shell), so the group number of element X in the periodic table is 6 + 10 = 16.

(ii) Element X has 3 electron shells (K, L and M) in its atom, so the period number of X is 3. That is, X belongs to 3rd period of the periodic table.

(iii) Element X has 6 valence electrons.

(iv) Element X has 6 valence electrons so it needs 2 more electrons to complete its octet (8 electrons in valence shell) and become stable. Thus, the valency of element X is 2.

Extra Questions for Class 10 Science Chapter 5 Short Answer Type II

Question 1.
Identify the elements with the following property and arrange them in increasing order of their reactivity.
(a) An element which is a soft and reactive metal.
(b) The metal which is an important constituent of limestone.
(c) The metal which exists in liquid state at room temperature.  [NCERT Exemplar]
Answer:
(a) Alkali metals are soft and reactive. For example, Na, K, etc.
(b) Limestone is calcium carbonate, therefore, the important constituent of limestone is calcium.
(c) Metals which exists in the liquid state at room temperature are Mercury (Hg).

Question 2.
List three main anomalies of Mendeleev’s classification of elements.
Answer:
Anomalies or defects of Mendeleev’s periodic classification of elements are as follows:

1. Position of hydrogen.
2. Position of isotopes: Isotopes of an element were not assigned separate places.
3. Elements which are chemically similar such as gold and platinum have been placed in separate groups.

Question 3.
(a) State modern periodic law.
(b) What are the advantages of the long form of the periodic table over Mendeleev’s periodic table?
Answer:
(a) According to modern periodic law “physical and chemical properties of elements are periodic function of their atomic numbers”.

(b) (i) Classification of elements on the basis of atomic number is more closer to chemical properties.
(ii) No separate places for isotopes of an element are required.
(iii) In case of Ar and K, Ar has less atomic number so it should be placed before K according to the increasing order of atomic number.

Question 4.
Two elements X and Y have atomic number 12 and 17 respectively.
(i) Write the electronic configuration of both.
(ii) Which type of bond will they form?
(iii) Write the formula of the compound formed by their combination (in terms of X and Y).
Answer:
(i) The electronic configuration of element X (Z = 12) = 2, 8, 2
The electronic configuration of element Y (Z = 17) = 2, 8, 7

(ii) The bond formed will be of ionic nature. One atom of X will transfer 1 electron each to two atoms of Y.

(iii) The formula of the compound is:

Question 5.
Name:
(a) Three elements that have a single electron in their outermost shells.
(b) Two elements that have two electrons in their outermost shells.
(c) Three elements with filled outermost shells.
Answer:
(a) Lithium (Li), Sodium (Na), Potassium (K)
(b) Magnesium (Mg), Calcium (Ca)
(c) Helium (He), Neon (Ne), Argon (Ar)

Question 6.
Two elements X and Y belong to group 1 and 2 respectively in the same period of periodic table. Compare them with respect to:   [CBSE 2011]
(i) the number of valence electrons in their atoms
(ii) their valencies
(iii) metallic character
(iv) the sizes of their atoms
(v) the formulae of their oxides
(vi) the formulae of their chlorides.
Answer:
X and Y belong to same period.

• X belongs to group ‘1’.
• Y belongs to group ‘2’.

(i) Valence electron in X is 1 whereas valence electrons in Y are 2.
(ii) The valency of X is 1 whereas valency of Y is 2.
(iii) X is more metallic than Y because metallic character decreases on moving from left to right in a period.
(iv) The size of X is more than Y because size of the atom decreases on moving from left to right in a period.
(v) Oxide of X = X₂O,   Oxide of Y = YO
(vi) Chloride of X = XCl,   Chloride of Y = YCl₂

Question 7.
The element Li, Na and K, each having one valence electron, are in period 2, 3 and 4 respectively of the Modem Periodic Table.
(a) In which group of the periodic table should they be?
(b) Which one of them is least reactive?
(c) Which one of them has the largest atomic radius? Give reason to justify your answer in each case. [CBSE 2013]
Answer:
(a) Since the elements have one valence electron, they are placed in group 1 (Alkali metals) in the order Li (period = 2); Na (period = 3); K (period = 4).

(b) Since the reactivity of the elements increases down a group, the element Li is the least reactive chemically.

(c) Since the atomic size increases down a group, the element K has the large atomic size or atomic radius out of these elements.

Question 8.
Explain why are the following statements not correct:
(a) All groups contain metals and non-metals.
(b) Atoms of elements in the same group have the same number of electron(s).
(c) Non-metallic character decreases across a period with increase in atomic number.
(d) Reactivity increases with atomic number in a group as well as in a period.   [2010]
Answer:
(a) Because all groups do not contain metals and non-metals. For example, Alkali metal group contains metals only.
(b) Atom of the elements in the same group have same number of electrons in the valence shell.
(c) Non-metallic character increases across a period with increase in atomic number.
(d) Reactivity increases with atomic number in a group but not across a period.

Question 9.
This question refers to the elements of the periodic table with atomic numbers from 3 to 18. Some of the elements are shown by letters but the letters are not the usual symbols of the elements.

(a) Which of these
(i) are noble gases?
(ii) are halogens?
(iii) are alkali metals?
(b) If A combines with F, what would be the formula of the resulting compound?
(c) What is the electronic configuration of G?
Answer:
(a) (i) H, P;
(ii) G, O;
(iii) A, I
(b) F
(c) 2, 7

Question 10.
Name two other elements which are in the same group as:
(i) Carbon
(ii) Fluorine
(iii) Sodium, respectively.
Answer:
(i) The two other elements which are in the same group as carbon are: Silicon (Si) and germanium (Ge).
(ii) The two other elements which are in the same group as fluorine are : Chlorine (Cl) and bromine (Br).
(iii) The two other elements which are in the same group as sodium are : Lithium (Li) and potassium (K).

Question 11.
Atomic number of an element is 16. Predict
(i) the number of valence electrons in its atom
(ii) its valency
(iii) its group number
(iv) whether it is a metal or a non-metal
(v) the nature of oxide formed by it.
(vi) the formula of the chloride   [CBSE2011]
Answer:
The element with atomic number Z = 16 is sulphur. The electronic configuration of the element is 2, 8, 6.
(i) The number of valence electrons is 6
(ii) The valency of the element is 2 (8 – 6 = 2)
(iii) The group number of the element is 16.
(iv) The element is a non-metal.
(v) Since the element is non-metal, its oxide is acidic in nature. Actually, two oxides are formed. These are SO₂ and SO₃. Both are of acidic nature.
(vi) The formula of the chloride is SCl₂.

Question 12.
(a) How are the following related?
(i) Number of valence electrons of the different elements present in the same group.
(ii) Number of the shells of the elements in the same period.
(b) How do the following change:
(i) Number of shells of the elements as we go down a group.
(ii) Number of valence electrons of elements on moving from left to right in a period.
(iii) Atomic radius in moving from left to right along a period.
(iv) Atomic size down a group. [CBSE 2012]
Answer:
(a) (i) Number of valence electrons of the elements present in a group do not change.
(ii) The elements present in the same period have same number of shells.

(b) (i) The number of shells of elements in a group gradually increase downwards.
(ii) The number of valence electrons of the elements in moving from left to right along a period gradually increase.
(iii) Atomic radius decreases from left to the right.
(iv) Atomic size increases down a group.

Question 13.
(a) What is meant by periodicity in properties of elements with reference to the periodic table?
(b) Why do all the elements of the same group have similar properties?
(c) How will the tendency to gain electrons change as we go from left to right across a period? Why?
Answer:
(a) Periodicity in properties of elements with reference to the periodic table means the elements having similar properties are repeated after certain intervals or periods and the elements are arranged in the tabular form.

(b) All the elements of the same group have similar properties because all the elements belonging to the same group of the Periodic Table have same number of valence electrons.

(c) On moving from left to right in a period, the tendency of atoms to gain electrons increases because on moving from left to right in a period the nuclear charge (positive charge on nucleus) increases due to gradual increase in the number of protons so it becomes easier for the atoms to gain electrons.

Question 14.
What is meant by ‘group’ in the modern periodic table? How do the following change on moving from top to bottom in a group?
(i) Number of valence electrons
(ii) Number of occupied shells
(iii) Size of atoms
(iv) Metallic character of elements
(v) Effective nuclear change experienced by valence electrons.  [CBSE 2014]
Answer:
The vertical columns in a periodic table are called groups.
(i) All the elements of a group have the same number of valence electrons.
(ii) On moving down in a group the number of occupied (filled) shells increases gradually.
(iii) On going down in a group the size of atoms increases because a new shell of electrons is added to the atoms at every step.
(iv) On going down in a group the metallic character of elements increases.
(v) On moving down in a group, one more electron shell is added at every stage and size of the atom increases. Thus valence electrons move more and more away from the nucleus and hold of the nucleus or nuclear charge on valence electrons decreases.

Question 15.
The elements Be, Mg and Ca each having two electrons in their outermost shells are in periods 2, 3, and 4 respectively of the modern periodic table. Answer the following questions, giving justification in each case:  [CBSE 2014]
(i) Write the group to which these elements belong.
(ii) Name the least reactive element.
(iii) Name the element having largest atomic radius.
Answer:

(i) All these elements belong to the 2nd group all have two electrons in their outermost shell.

(ii) Be is the least reactive metal because reactivity of metals increases in a period as the tendency to lose electrons in a group increases.

Therefore, Be being the smallest in all the given elements of a period has its valance electrons nearest to the nucleus. So the removal of electrons from its valance shell will be difficult.

(iii) Ca has the largest atomic radius because it has maximum number of shells, i.e., 4.

Question 16.
An element ‘M’ with electronic configuration (2, 8, 2) combines separately with (NO₃)^–, (SO₄)^2- and (PO₄)^3- radicals. Write the formula of three compounds so formed. To which group and period of the Modern Periodic Table does the elements ‘M’ belong? Will ‘M’ from covalent or ionic compounds? Give reason to justify your answer.
Answer:
Element M with electronic configuration =

Total number of electrons = 2 + 8 + 2 = 12, i.e., the given element is Magnesium (Mg). Formula of compound formed are:

Formula of compound = Mg (NO₃)₂

Formula of compound = MgSO₄

Formula of compound = Mg₃ (PO₄)₂

M will form ionic compound with radicals given. An ionic compound is a chemical compound comprising ions held together by electrostatic forces. In this compound no sharing of electrons takes place.

Extra Questions for Class 10 Science Chapter 5 Long Answer Type

Question 1.
An element X which is a yellow solid at room temperature shows catenation and allotropy. X forms two oxides which are also formed during the thermal decomposition of ferrous sulphate crystals and are the major air pollutants.
(a) Identify the element X
(b) Write the electronic configuration of X
(c) Write the balanced chemical equation for the thermal decomposition of ferrous sulphate crystals.
(d) What would be the nature (acidic/basic) of oxides formed?
(e) Locate the position of the element in the Modern Periodic Table.  [NCERT Exemplar]
Answer:
(a) The element X which is a yellow solid at room temperature and shows catenation and allotropy is sulphur (S).

(b) The atomic number of sulphur is 16. Therefore, its electronic configuration is 2, 8, 6.

(c)

Both SO₂ and SO₃ are major air pollutants.

(d) Since sulphur is a non-metal, therefore, both SO₂ and SO₃ are acidic oxides since they dissolve in water to form the corresponding acids.

(e) Since sulphur contains six valence electrons, therefore, it lies in group 6 + 10 = 16. Further, since atomic number of sulphur (S) is 16, it lies in the 3rd period.

Question 2.
An element X (atomic number 17) reacts with an element Y (atomic number 20) to form a divalent halide.
(a) Where in the periodic table are elements X and Y placed?
(b) Classify X and Y as metal, non-metal or metalloid.
(c) What will be the nature of oxide of element Y? Identify the nature of bonding in the compound formed.
(d) Draw the electron dot structure of the divalent halide.   [NCERT Exemplar]
Answer:
(a) X belongs to Group 17 and 3^rd Period.
Y belongs to Group 2 and 4^th Period.
(b) X-non-metal and Y-metal.
(c) Basic oxide; Ionic bonding.
(d)

Question 3.
(a) Why do we classify elements?
(b) What were the two criteria used by Mendeleev in creating his Periodic Table?
(c) Why did Mendeleev leave some gaps in his Periodic Table?
(d) In Mendeleev’s Periodic Table, why was there no mention of Noble gases like Helium, Neon and Argon?
(e) Would you place the two isotopes of chlorine, Cl-35 and Cl-37 in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.
Answer;
(a) As different elements were being discovered, scientists gathered more information about the properties of these elements. It was observed that it was difficult to organise all the information or properties of these elements. So scientists started discovering some pattern in their properties to classify all the known elements to make their study easier.

(b) Atomic mass and similarity of chemical properties (compounds formed by elements with oxygen and hydrogen) were the two criteria used by Mendeleev in his Periodic Table.

(c) Mendeleev left some gaps in his Periodic Table as he predicted the existence of some elements that had not been discovered at that time.

(d) Noble gases like helium, neon, argon, etc. were not mentioned in Mendeleev’s Periodic Table because these gases were discovered later as they are very inert and present in extremely low concentrations in our atmosphere. After the discovery of noble gases they could be placed in a new group without disturbing the existing order of the Periodic Table.

(e) The Modem Periodic Table states that properties of elements are a periodic function of their atomic numbers, since Cl-35 and Cl-37 isotopes have the same atomic number (17), hence they will have same chemical properties even though their atomic masses are different. So, they should be placed in the same slot of the periodic table.

Question 4.
Atomic number of a few elements are give below:
10, 20, 7, 14
(a) Identify the elements.
(b) Identify the Group number of these elements in the Periodic Table.
(c) Identify the Periods of these elements in the Periodic Table.
(d) What would be the electronic configuration for each of these elements?
(e) Determine the valency of these elements.  [NCERT Exemplar]
Answer:
(a) The element are: Neon (Z = 10), Calcium (Z = 20), Nitrogen (Z = 7) and Silicon (Z = 14).
(b) Group number: Neon (18), Calcium (2), Nitrogen (15), Silicon (14).
(c) Periods: Neon (2), Calcium (4), Fluorine (2), Silicon (3).
(d) Electronic Configuration: Neon (2, 8); Calcium (2, 8, 8, 2); Nitrogen (2, 5); Silicon (2, 8, 4).
(e) Valency: Neon (zero); Calcium (2); Nitrogen (3); Silicon (4).

Question 5.
This question refers to the elements of the periodic table with atomic numbers from 3 to 18. Some of the elements are shown by letters, but the letters are not the usual symbols of the elements.

(a) Which of these:
(i) is a noble gas?
(ii) is a halogen?
(iii) is an alkali metal?
(iv) is an element with valency 4?
(b) If A combines with F, what would be the formula of the resulting compound?
(c) What is the electronic arrangement of G?
Answer:
(a) (i) G having 8 electrons in its valence shell is a noble gas.
₁₀G : 2, 8

(ii) F having 7 electrons in its valence shell is a halogen.
₁₇F : 2, 8, 7

(iii) B having 1 electron in its valence shell is an alkali metal.
₁₁B : 2, 8, 1
Element A is also an alkali metal.
₃A : 2, 1

(iv) The element D having 4 electrons in its valence shell will have valency 4.
₁₄D : 2, 8, 4

(b) A is an electropositive element with valency 1 while F is an electronegative element with valency 1.
Hence, the formula of the compound between A and F would be AF.

(c) The electronic configuration of G is:
₁₀G : 2, 8.

Question 6.
The elements of one short period of the periodic table are given below in the order from left to right.
Li, Be, B, C, O, F, Ne,
(a) To which period these elements belong?
(b) One element of this period is missing. Which is the missing element and where should it be placed?
(c) Which one of the element in this period shows the property of catenation?
(d) Place the three elements fluorine, beryllium and nitrogen in the order of increasing electronegativity.
(e) Which one of the above elements belong to the halogen series?
Answer:
(a) Second period (Atomic number: 3-10)
(b) Nitrogen (N), It should be placed between Carbon (Atomic number 6) and Oxygen (Atomic number 8)
(c) Carbon
(d) Be, N, F
(e) Fluorine.

Question 7.
Which element has
(a) two shells, both of which are completely filled with electrons?
(b) the electronic configuration 2, 8, 2?
(c) a total of three shells, with four electrons in its valence shell?
(d) a total of two shells, with three electrons in its valence shell?
(e) twice as many electrons in its second shell as in its first shell?
Answer:
(a) Neon [Ne] (2, 8)
(b) Magnesium [Mg]
(c) Silicon [Si] (2, 8, 4)
(d) Boron [B] (2, 3)
(e) Carbon [C] (2, 4).

Periodic Classification of Elements HOTS Questions With Answers

Question 1.
(a) In this ladder symbols of elements are jumbled up. Rearrange these symbols of elements in the increasing order of their atomic number in the Periodic Table.
(b) Arrange them in the order of their group also.  [NCERT Exemplar]

Answer:
(a) H, He, Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca
(b) Group 1 – H, Li, Na, K
Group 2 – Be, Mg, Ca
Group 13 – B, Al
Group 14 – C, Si
Group 15 – N, P
Group 16 – O, S
Group 17 – F, Cl
Group 18 – He, Ne, Ar.

Question 2.
The electronic configuration of an element T is 2, 8, 7.
(а) What is the group number of T?
(b) What is the period number of T?
(c) How many valence electrons are there in an atom of T?
(d) Is it a metal or non-metal?
Answer:
(a) Group-17
(b) Third period
(c) 7
(d) Non-metal.

Question 3.
Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.
(a) Name the elements which have taken the place of these elements.
(b) Mention the group and the period of these elements in the Modern Periodic Table.
(c) Classify these elements as metals, non-metals or metalloids.
(d) How many valence electrons are present in each one of them?  [NCERT Exemplar]
Answer:
(a) Eka-silicon for germanium (Ge) and Eka-aluminium for Gallium (Ga).
(b) Group number of Ga is 13 and its period is 4^th and group number of Ge is 14 and its period is also 4^th.
(c) Both Ga and Ge are metalloids.
(d) Ga lies in group 13, therefore, it has 13 – 10 = 3 valence electrons. Similarly, Ge lies in group 14 and hence it has 14 – 10 = 4 valence electron.

Question 4.
The atomic numbers of three elements A, B and C are given below:

(i) Which element belongs to group-18?
(ii) Which element belongs to group-5?
(iii) Which element belongs to group-3?
(iv) To which period/periods do these elements belong?
Answer:
(i) C
(ii) B
(iii) A
(iv) Second period.

Question 5.
(a) Electropositive nature of the element(s) increases down the group and decreases across the period.
(b) Electronegativity of the element decreases down the group and increases across the period.
(c) Atomic size increases down the group and decreases across a period (left to right).
(d) Metallic character increases down the group and decreases across a period.
On the basis of the above trends of the Periodic Table, answer the following about the elements with atomic numbers 3 to 9.
(a) Name the most electropositive element among them
(b) Name the most electronegative element
(c) Name the element with smallest atomic size
(d) Name the element which is a metalloid
(e) Name the element which shows maximum valency.  [NCERT Exemplar]
Answer:
(a) Lithium (Z = 3) is the most electropositive element.
(b) Fluorine (Z = 9) is the most electronegative element.
(c) Fluorine (Z = 9) has the smallest atomic size.
(d) Boron (Z = 5) is a metalloid.
(e) Carbon (Z = 6) shows the maximum valency (4).
However, the element nitrogen (Z = 7) can show valency 5 in some compounds (example, N₂O₅).

Question 6.
The following table shows the position of six elements A, B, C, D, E and F in the period table.

Using the above table answer the following questions:
(a) Which element will form only covalent compounds?
(b) Which element is a metal with valency of 2?
(c ) Which element is a non-metal with valency of 3?
(d) Out of D and E, which one has more atomic radius and why?
(e) Write a common name for the family of elements C and F.
Answer:
(a) The element ‘E’ present in group 14 is a non-metal. Its name is silicon (Si) and the compounds of the element are only covalent.
(b) The element ‘D’ present in group 2 is a metal known as magnesium (Mg). It exhibits valency 2 in its compounds.(c) The elements ‘B’ present in group 15 is a non-metal. It is nitrogen (N) and exhibits valency 3 in its compounds.
(d) The element ‘D’ has more atomic radius than the element ‘E’ as the atomic size decreases along a period.
(e) The elements ‘C’ and ‘F’ present in group 18 belong to a family known as noble gases.

Question 7.
From the part of the periodic table given, answer the following questions

(a) Which is the most reactive metal?
(b) Name the family of L, Q, R and T.
(c) Name one element of group 2 and 15.
(d) Name one member of group 18 other than neon.
(e) Give the name of the element S placed below carbon in group 14.
Answer:
(a) Z
(b) L, Q, R and T belongs to halogen family.
(c) Group-2 element – Ca, Mg
Group-15 element – N, P
(d) The element argon (Ar) is also present in group 18.
(e) The element is silicon (Si).

Extra Questions for Class 10 Science Chapter 5 Value Based Questions

Question 1.
First systematic classification was done by Mendeleev. He arranged the elements in the increasing order of atomic masses. Elements with similar properties lies in a group, he left certain gaps for unknown elements.
(i) Name two elements for which blank spaces were left out by Mendeleev.
(ii) List two main drawbacks of the Mendeleev’s periodic classification.
(iii) Mention the values exhibited by Mendeleev.
Answer:
(i) Gallium (Ga), Germanium (Ge).
(ii) (a) Position of hydrogen.
(b) Position of isotopes.
(iii) Use of knowledge of Chemistry, Thinking ability.

Question 2.
Ria and Ram are students of class X. Ria is very organised and systematic. The teachers love her. She earns a great respect in the class whereas Ram is unorganised and always faces a lot of problem in handling life situations.
(i) In your opinion how does the organisation help in daily life?
(ii) How can you relate the above fact with the chapter classification of elements. How does classification of elements help us in studying them properly?
Answer:
(i) Organised approach always make the work easier and quicker. Hence, classification makes the things easier.

(ii) Organised approach in classification of elements make the study easier and we get a group of elements with similar properties.
By this approach we can study the elements easily which lies in a group with similar chemical properties.

In this page, we are providing Metals and Non-metals Class 10 Extra Questions and Answers Science Chapter 3 pdf download. NCERT Extra Questions for Class 10 Science Chapter 3 Metals and Non-metals with Answers will help to score more marks in your CBSE Board Exams.

Class 10 Science Chapter 3 Extra Questions and Answers Metals and Non-metals

Extra Questions for Class 10 Science Chapter 3 Metals and Non-metals with Answers Solutions

Extra Questions for Class 10 Science Chapter 3 Very Short Answer Type

Question 1.
Name the property due to which metals have a shining surface in their pure state.
Answer:
Metallic lustre.

Question 2.
Name two most malleable metals.
Answer:
Gold and silver.

Question 3.
Name the most ductile metal.
Answer:
Gold.

Question 4.
Name a metal which occurs in the free state.
Answer:
Gold.

Question 5.
Give an example of an elementary substance which is a good conductor of electricity but is not a metal.
Answer:
Graphite.

Question 6.
Name two metals which are both malleable and ductile.
Answer:
Silver and gold.

Question 7.
Name the non-metal which is a liquid.
Answer:
Bromine.

Question 8.
Expand PVC.
Answer:
Polyvinyl chloride.

Question 9.
Name a non-metal which is lustrous.
Answer:
Iodine.

Question 10.
Metal A can displace metal B from BO, the oxide of metal B. Metal B can displace C from solution of CSO₄, the sulphate of metal C. Arrange metal A, B and C in the order of increasing reactivity.
Answer:
C < B < A.

Question 11.
Name two metals which can be cut with a knife.
Answer:
Lithium, sodium, potassium

Question 12.
An element forms an oxide A₂O₃ which is acidic in nature. Identify A as a metal or non-metal.  [NCERT Exemplar]
Answer:
Oxides of non-metals are acidic in nature while those of metals are basic in nature. Hence, A must be a non-metal.

Question 13.
Why does calcium float in water?
Answer:
Calcium reacts with water to form calcium hydroxide and hydrogen. Bubbles of hydrogen gas stick to the surface of calcium, hence it floats.

Question 14.
Arrange the following metals in the decreasing order of reactivity Na, K, Cu, Ag.
Answer:
K > Na > Cu > Ag.

Question 15.
Name the two metals which do not react with water at all.
Answer:
Lead, Copper, Silver and Gold

Question 16.
Name the element which shows non-metallic properties, but is also present in the activity series of metal.
Answer:
Hydrogen.

Question 17.
If X, Y, Z, W, A, B and C represents the metals in the decreasing order of their reactivity, which metal is most likely to occur in free state in nature?
Answer:
C is least reactive, hence .it is likely to occur in the free state.

Question 18.
Name any one metal which reacts neither with cold water nor with hot water, but reacts with heated steam to produce hydrogen gas.
Answer:
Iron
3Fe (s) + 4H₂O (g) → Fe₃O₄ (s) + 4H₂ (g)

Question 19.
Mention the composition of aqua regia.
Answer:
It is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1.

Question 20.
In nature, metal A is found in the free state, while metal B is found in the form of its compounds. Which of these two will be nearer to the top of the activity series of metals?
Answer:
Metal B will be nearer to the top because it is more reactive as it is clear from the fact that it exists in the form of its compounds.

Question 21.
Name any two oxides ores.
Answer:

1. Haematite
2. Bauxite.

Question 22.
Which method is used for the concentration of sulphide ores?
Answer:
Froth flotation process.

Question 23.
Complete the chemical equation.

Answer:

Question 24.
What is galvanisation?
Answer:
Galvanisation is a method of protecting steel and iron from rusting by coating them with a thin layer of zinc.

Question 25.
24 Carat gold is not suitable for making jewellery. Why?
Answer:
24 carat gold is very soft, so it is alloyed with either silver or copper to make it hard.

Question 26.
How many carats is pure gold?
Answer:
24 carat.

Question 27.
Name the metal which is used for galvanising iron.
Answer:
Zinc (Zn).

Question 28.
What is meant by 22 carat gold?
Answer:
An alloy consisting of 22 parts by weight of pure gold and 2 parts by weight of copper or silver is called 22 carat gold.

Question 29.
What is an alloy?
Answer:
An alloy is a homogeneous mixture of two or more metals or a metal and a non-metal.

Question 30.
Why do shopkeepers apply oil on tools made of iron while storing them?
Answer:
To protect them from rusting as the oxygen and moisture of the atmosphere will not be able to come in direct contact with the surface of iron.

Question 31.
State two conditions for the rusting of iron.
Answer:

1. Presence of air (or oxygen).
2. Presence of water (or moisture).

Question 32.
Name two metals which are highly resistant to corrosion.
Answer:
Gold and platinum.

Question 33.
Name the gas in air which tarnishes silver particles slowly.
Answer:
Hydrogen sulphide (H₂S).

Extra Questions for Class 10 Science Chapter 3 Short Answer Type I

Question 1.
What happens when
(a) ZnCO₃ is heated in the absence of oxygen?
(b) a mixture of Cu₂O and Cu₂S is heated? [NCERT Exemplar]
Answer:
(a) A mixture of ZnO(s) and CO₂ is formed.

(b) A mixture of copper and SO₂ is formed.

Question 2.
Using the electronic configurations, explain how magnesium atom combines with oxygen atom to form magnesium oxide by transfer of electrons.
Answer:

Question 3.
Name two metals which react violently with cold water. Write any three observations you would make when such a metal is dropped into water. How would you identify the gas evolved, if any, during the reaction?   [CBSE 2008]
Answer:
Sodium, Potassium
When these metals are dropped in water, bubbles will be evolved due to evolution of hydrogen gas.
The gas will catch fire and the solution will be alkaline, i.e., it will turn red litmus blue.

Test: When a burning matchstick is brought near the gas, it burns explosively with a ‘pop’ sound and the splinter is extinguished.

Question 4.
State reasons for the following:
(i) Electric wires are covered with rubber-like material.
(ii) From dilute hydrochloric acid, zinc can liberate hydrogen gas but copper cannot.
Answer:
(i) It is because rubber is an insulator and does not allow current to flow through it.
(ii) Zinc is is placed above hydrogen in the reactivity series of metals while copper is placed below it. Metals placed above hydrogen can displace hydrogen from water and acids while those below it cannot. Therefore, zinc can displace hydrogen from dilute HCl whereas copper cannot.

Question 5.
Give the formulae of the stable binary compounds that would be formed by the combination of the following pairs of elements.
(a) Mg and N₂
(b) Li and O₂
(c) Al and Cl₂
(d) K and O₂
Answer:
(a) Mg₃N₂
(b) Li₂O
(c) AlCl₃
(d) K₂O

Question 6.
Compound X and aluminium are used to join railway tracks.
(a) Identify the compound X
(b) Name the reaction
(c) Write down its reaction.  [NCERT Exemplar]
Answer:
(a) Compound X must be iron (III) oxide, Fe₂O₃.
(b) The reaction is known as ‘thermite reaction’ or ‘aluminothermy’.
(c) The reaction is carried out by igniting the mixture with a Mg-ribbon.

Question 7.
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer:
Zinc and magnesium can displace hydrogen from dilute acids whereas copper and silver cannot. The metals lying above hydrogen in the reactivity series can displace hydrogen on reaction with dilute acids.

Question 8.
During extraction of metals, electrolytic refining is used to obtain pure metals,
(a) Which material will be used as anode and cathode for refining of silver metal by this process?
(b) Suggest a suitable electrolyte also,
(c) In this electrolytic cell, where do we get pure silver after passing electric current?  [NCERT Exemplar]
Answer:
In the electrolytic refining of impure silver metal:
(a) A rod of impure silver is used as anode while that of pure silver as cathode.
(b) The electrolyte is a water soluble salt of silver, for example silver chloride or silver nitrate.
(c) On passing current, pure silver gets deposited at the cathode. It can be scrapped off later on.

Question 9.
Give reason for the following:
(i) Iron grills are frequently painted.
(ii) Gold ornaments retain their lustre even after several years of use.
Answer:
(i) Iron metal easily gets rusted by air containing moisture and oxygen. Therefore, iron grills are frequently painted with rust proof paints.
(ii) Gold is a noble metal and is not affected by chemicals or by air. Therefore, gold ornaments retain their lustre even after several years.

Question 10.
Name two metals which can be used to reduce metal oxides to metal.
Answer:
(i) Aluminium (Al)

(ii) Magnesium (Mg)

Question 11.
Give the reaction involved during extraction of zinc from its ore by
(a) roasting of zinc ore
(b) calcination of zinc ore   [NCERT Exemplar]
Answer:
(a) Roasting is done for the sulphide ore (zinc blende).

(b) Calcination is done for the carbonate ore (calamine).

Question 12.
The following reaction takes place when aluminium powder is heated with MnO2
3MnO₂(s) + 4Al(s) → 3Mn(l) + 2Al₂O₃(l) + Heat [NCERT Exemplar]
(a) Is aluminium getting reduced?
(b) Is MnO₂ getting oxidised?
Answer:
(a) Aluminium is getting oxidised to Al₂O₃.
(b) Manganese dioxide is getting reduced to Mn.

Question 13.
Differentiate between roasting and calcination process used in metallurgy. Give one example of each.
Answer:

Question 14.
Write chemical equations for the reactions taking place when
(a) Magnesium ribbon is burnt in a jar containing oxygen
(b) Sodium metal falls into a sink containing water
Answer:
(a)

(b) 2Na + 2H₂O → 2NaOH + H₂

Question 15.
What is an amalgam? Write the constituent metals of brass.
Answer:
An amalgam is an alloy in which one of the metals is mercury.
Brass is an alloy of copper and zinc (Cu and Zn). It contains 80% copper and 20% zinc.

Question 16.
Every ore is a mineral but not every mineral is an ore. Explain.
Answer:
Every mineral is not suitable for the extraction of the metal. The mineral from which the metal is economically and conveniently extracted is called an ore.

Extra Questions for Class 10 Science Chapter Short Answer Type II

Question 1.
What is an alloy? How is it prepared? Name the alloy which is used for welding electrical wires together.
Answer:
Alloy is a mixture of two or more metals or non-metals.
Alloys are made by mixing the metals in their molten state. It is prepared by first melting the primary metal and then dissolving the other metal in definite proportion. It is then cooled to room temperature. Solder is used for welding electrical wires together.

Question 2.
Give reasons for the following observations:
(i) Ionic compounds in general have high melting and boiling points.
(ii) Highly reactive metals cannot be obtained from their oxides by heating them with carbon.
(iii) Copper vessels get a green coat when left exposed to air in the rainy season.
Answer:
(i) Ionic compounds have high melting and boiling points due to strong force of attraction between oppositely charged ions.

(ii) It is because these metals, have great affinity towards oxygen and so cannot be reduced by carbon or carbon monoxide or hydrogen.

(iii) Copper vessels react with CO₂, O₂ and moisture to form green coloured basic copper carbonate [CuCO₃. CU(OH)₂] on their surface when exposed to moist air.

Question 3.
E is an element amongst copper, zinc, aluminium and iron. It shows the following properties:
Answer:
(a) One of its ores is rich in E₂O₃.
(b) E₂O₃ is not attacked by water.
(c) It forms two chlorides ECl₂ and ECl₃.
Name the element and justify your answer.
Answer:
The clue for the correct answer is the formation of ECl₂ and ECl₃. This shows that the element E has variable valencies of 2 and 3 out of the elements listed, only iron exists in divalent and trivalent forms.
(a) The ore rich in Fe₂O₃ is haematite.
(b) Haematite (Fe₂O₃) is not attacked by water.
(c) The two chlorides are: Iron (II) chloride or FeCl₂ and iron (III) chloride or FeCl₃.

Question 4.
When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved. [NCERT Exemplar]
Answer:
The base with molecular mass 40 is NaOH. Hence, the metal X must be sodium (Na). It reacts with H₂O to form the base NaOH and liberates H₂ gas which easily catches fire.

Question 5.
You are provided with three metals: Sodium, magnesium and copper. Using only water as the reactant, how will you identify them?
Answer:

• The metal which reacts violently with cold water and catches fire is sodium.
• The metal which evolves hydrogen gas upon heating with water is magnesium.
• The metal which does not react with water even on strong heating is copper.

Question 6.
A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas C causes global warming.
(a) Identify A, B and C.
(b) To which Group of Periodic Table does A belong?  [NCERT Exemplar]
Answer:
The non-metal A is carbon. It is an important constituent of our food in different forms. For example, glucose (C₆H₁₂O₆) contains carbon. In fact, all food materials are organic compounds and these contain carbon as an essential constituent. The two oxides of carbon are, carbon monoxide (B) and carbon dioxide (C). Carbon dioxide causes global warming.

(a) A = Carbon (C); B = Carbon monoxide (CO); C = Carbon dioxide (CO₂)
(b) Carbon is the first member of group 14 in the long form of periodic table.

Question 7.
A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.   [NCERT Exemplar]
Answer:
Non-metal ‘X’ must be carbon. It exist in two forms, diamond and graphite. Diamond is hardest natural substance. Hence, ‘Y’ is diamond. Graphite is a good conductor of electricity. Hence, ‘Z’ is graphite.

Question 8.
A metal E is stored under kerosene. When a small piece of it is left open in air, it catches fire. When the product formed is dissolved in water, it turns red litmus to blue.
(i) Name the metal E.
(ii) Write the chemical equation for the reaction when it is exposed to air and when the product is dissolved in water.
(iii) Explain the process by which the metal E is obtained from its molten chloride.
Answer:
(i) The available information suggests that the metal (E) is sodium (Na).

The solution is basic and it turns red litmus blue.
(iii) The metal is obtained by the process of electrolytic reduction.

Question 9.
Explain how the following metals are obtained from their compounds by reduction process:
(i) Metal X which is low in reactivity series
(ii) Metal Y which is in the middle of the series
(iii) Metal Z which is high up in the reactivity series.
Give one example of each type.
Answer:
(i) Metals which are low in reactivity series can be obtained by heating their compounds. For example, mercury is obtained by heating its ore, cinnabar (HgS), in air.
HgS + O₂ → Hg + SO₂

(ii) Metals which are in the middle of the series are generally obtained by heating their compounds with some reducing agent such as carbon. For example, iron is obtained from haematite (Fe₂O₃) by reduction with carbon.
2Fe₂O₃ + 3C → 4Fe + 3CO₂

(iii) Metals which are high up in the series are obtained by electrolytic reduction. For example, sodium is obtained by electrolysis of molten sodium chloride.

Question 10.
How is the method of extraction of metals high up in the reactivity series different from that for metal in the middle? Why the same process cannot be applied for them? Explain giving equations, the extraction of sodium.
Answer:
The metals placed high up in the reactivity series (e.g., Na, K, Ca, Mg, Al) are highly reactive and strong reducing agents and are extracted by carrying out the electro-reduction of their molten salts. On the other hand, metals placed in the middle of the series (e.g., Fe, Zn, Cd, Co, Ni, etc.) are comparatively less reactive and are extracted by roasting or calcination.

Sodium is extracted by electro-reduction process.
NaCl ⇌ Na⁺ + Cl^–
Reaction at the cathode: Na⁺ + e⁺ → Na⁺
Reaction at the anode: Cl^– – e^– → Cl
Cl + Cl → Cl₂

Question 11.
Write balanced chemical equation for the reactions taking place when
(i) zinc carbonate is calcinated.
(ii) zinc sulphide is roasted or heated in air.
(iii) zinc oxide is reduced to zinc.
Answer:

Extra Questions for Class 10 Science Chapter 3 Long Answer Type

Question 1.
Explain the following:
(a) Reactivity of Al decreases if it is dipped in HNO₃.
(b) Carbon cannot reduce the oxides of Na or Mg.
(c) NaCl is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state.
(d) Iron articles are galvanised.
(e) Metals like Na, K, Ca and Mg are never found in their free state in nature.   [NCERT Exemplar]
Answer:
(a) On dipping in HNO₃, the surface of Al is oxidised to form an oxide layer of Al₂O₃, which is hard and impervious. It acts as a protective layer for Al underneath. Hence, reactivity of Al decreases.

(b) Na or Mg are highly reactive metals. They have greater affinity for oxygen than for carbon. Hence, their oxides are stable. To reduce them with carbon, very high temperature is required. At this temperature, these metals react with carbon to form corresponding carbides.

(c) The conduction of electricity is due to movement of ions. In the solid state, Na⁺ and Cl^– are fixed and not free to move. Hence, it does not conduct electricity. In the aqueous solution or in the molten state, Na⁺ and Cl^– ions are free to move about and hence conduct electricity.

(d) Galvanisation means coating of iron articles with a layer of zinc. Zinc is more reactive than iron. Hence, it undergoes oxidation more readily than iron. As a result, iron articles remain protected.

(e) These metals are highly reactive and react with the gases present in the air. Hence, they are found as compounds in the ores and not in the free state in nature.

Question 2.
(i) Given below are the steps for extraction of copper from its ore. Write the reaction involved.
(a) Roasting of copper (I) sulphide.
(b) Reduction of copper (I) oxide with copper (I) sulphide.
(c) Electrolytic refining.
(ii) Draw a neat and well labelled diagram for electrolytic refining of copper.   [NCERT Exemplar]
Answer:
(i)

This reaction in which one of the reactants (Cu₂S) carries the reduction of the product (Cu₂O) is known as auto-reduction.

(c) Reaction taking place in electrolytic refining are:
At cathode (reduction): Cu²⁺(aq) + 2e^– → Cu(s)
At anode (oxidation): Cu(s) → Cu²⁺ (aq) + 2e^–

(ii) Metals like copper, aluminium and zinc are refined by this process.

Question 3.
(a) In the formation of compound between two atoms A and B, A loses two electrons and B gains one electron.
(i) What is the nature of the bond between A and B?
(ii) Suggest the formula of the compound formed between A and B.
(b) On similar lines explain the formation of MgCl₂ molecule.
(c) Common salt conducts electricity only in the molten state. Why?
(d) Why is melting point of NaCl high?
Answer:
(a) (i) Ionic bond

(b) Mg → Mg²⁺ + 2e^–
2Cl + 2e^– → 2Cl^–

(c) Na⁺ and Cl^– ions are free to move in molten state but not in solid state.

(d) It is due to strong force of attraction between Na⁺ and Cl^–.

Question 4.
Two ores A and B were taken. On heating ore A gives CO₂ whereas, ore B gives SO₂. What steps will you take to convert them into metals?  [NCERT Exemplar]
Answer:
Since ore A gives CO₂ and ore B gives SO₂. Therefore, ores are MCO₃ and MS.
A can be obtained

B can be obtained

Metals and Non-metals HOTS Questions With Answers

Question 1.
An element A burns with a golden yellow flame in air. It reacts with another element B,
atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.  [NCERT Exemplar]
Answer:
A = Sodium which burns with golden flame in air. It reacts with chlorine (Z = 17) to form sodium chloride.
2Na (s) + Cl₂ (g) → 2NaCl (s)

Hence, B = chlorine and C = sodium chloride

Hence, D = Sodium hydroxide.

Question 2.
What is meant by reactivity series of metals? State which of the following chemical reactions will take place giving suitable reason for each.
I. Zn (s) + CuSO₄ (aq) → ZnSO₄ (aq) + Cu (s)
II. Fe (s) + ZnSO₄ (ag) → FeSO₄ (aq) + Zn (s)
III. Zn (s) + FeSO₄ (aq) → ZnSO₄ (aq) + Fe (s)
Answer:
Reactivity series is a list of metals arranged in the order of their decreasing reactivities (activities).
I. Reaction will take place because Zn is above Cu in the activity series and is more reactive than Cu.
II. Reaction will not take place as Fe is below Zn in the activity series and cannot displace Zn from its solution.
III. Reaction will take place because Zn is more reactive than Fe.

Question 3.
A student has been collecting silver coins and copper coins. One day, she observed a black coating on silver coins and a green coating on copper coins. Which chemical phenomenon is responsible for these coatings? Write the chemical name of black and green coatings.
Answer:
The name of the phenomenon is corrosion. The chemical name of black coating is silver sulphide (Ag₂S) formed due to attack of H₂S gas present in the atmosphere on silver and that of green coating is basic copper carbonate formed due to attack of moist air (CO₂, O₂ and H₂O vapours) on copper.

Question 4.
Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in the reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both the reactions.    [NCERT Exemplar]
Answer:
The divalent element M is a metal. It reacts with both sodium hydroxide (alkali) and dilute hydrochloric acid to evolve hydrogen gas.
M(s) + 2NaOH (aq) → Na₂MO₂ (aq) + H₂(g)
M(s) + 2HCl (aq) → MCl₂ (aq) + H₂(g)
The gas burns with a pop sound when a burning matchstick is brought near it.

Question 5.
A non-metal A which is the largest constituent of air, when heated with H₂ in 1: 3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with O₂ it gives an oxide C. If this oxide is passed into water in the presence of air it gives an acid D which acts as a strong oxidising agent.
(a) Identify A, B, C and D.
(b) To which group of periodic table does this non-metal belong?  [NCERT Exemplar]
Answer:
Non-metal which is the largest constituent of air is nitrogen (N₂). Hence, A = N₂.
When heated with H2 in presence of Fe as catalyst, it forms ammonia (NH₃).

Hence, B = NH₃.
When heated with O₂, it forms nitric oxide (NO).

NO further gets oxidised to NO2 by O2 of the air.
2NO(g) + O₂(g) → 2NO₂(g)
Hence, C = NO₂.

On passing this oxide into water in presence of air (O₂), it gives nitric acid (HNO₃) which is a strong oxidising agent.
4NO₂(g) + 2H₂O(l) + O₂(g) → 4HNO₃(aq)
Hence, D = HNO₃.
Nitrogen belongs to Group 15.

Extra Questions for Class 10 Science Chapter 3 Value Based

Question 1.
Anil and his neighbour Sunil had got their garden fenced with iron rods. Next day Anil saw that Sunil was painting the iron fence. Sunil suggested Anil to do the same to increase the longevity of the iron rods by preventing corrosion. Anil argued that it is a waste of time and his iron rods were strong enough. After reading the above passage, answer the following questions.
(i) Whose opinion was correct? Justify.
(ii) Mention two methods (other than painting) to prevent iron from corrosion.
(iii) What is the chemical formula of rust?
(iv) Mention the values exhibited by Sunil.
Answer:
(i) Sunil’s opinion is correct, it helps to protect iron rods from rusting/corrosion.
(ii) (a) Galvanisation
(b) Cathodic protection
(iii) Fe₂O₃. xH₂O
(iv) Friendship/use of knowledge of Chemistry

Question 2.
Mohan approached a goldsmith and asked him to make some gold ornaments. For this he gave advance money also and demanded that 100% pure gold ornaments be made. The goldsmith suggested Mohan that 22-carat gold ornaments would be more appropriate than 24-carat.
(i) What is the difference between 24-carat gold and 22-carat gold?
(ii) Calculate the % of gold in 22-carat gold.
(iii) Why did the goldsmith suggested for use of 22-carat gold?
(iv) Mention the values exhibited by the goldsmith.
Answer:
(i) 24-carat gold is pure gold (100% pure gold) while 22-carat gold is comparatively less pure.
(ii) % of gold in 22 carat = 100 = 91.7%
(iii) Pure of 24-carat gold is very soft, little malleable and ductile. It is quite difficult to work on it. But 22 carat gold (alloy) is comparatively hard, more malleable and ductile.
(iv) Use of knowledge of chemistry, truth, honesty and professionalism.