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CBSE Sample Papers for Class 9 Science Paper 7 are part of CBSE Sample Papers for Class 9 Science. Here we have given CBSE Sample Papers for Class 9 Science Paper 7.

CBSE Sample Papers for Class 9 Science Paper 7

Students who are going to appear for CBSE Class 9 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 7 of Solved CBSE Sample Paper for Class 9 Science is given below with free PDF download solutions.

Time Allowed : 3 Hours
Max. Marks: 80

General Instructions

• The question paper comprises of two Sections, A and B. You are to attempt both the sections.
• All questions are compulsory. However an internal choice will be provided in two questions of 3 marks each and one question of five marks.
• All questions of Section A and all questions of Section B are to be attempted separately.
• Question numbers 1 to 2 in Section A are one-mark questions. These are to be answered in one word or in one sentence.
• Question numbers 3 to 5 in Section A are two-marks questions. These are to be answered in about 30 words each.
• Question numbers 6 to 15 in Section A are three-marks questions. These are to be answered in about 50 words each.
• Question numbers 16 to 21 in Section A are five-marks questions. These are to be answered in about 70 words each.
• Question numbers 22 to 27 in Section B are two-marks questions based on practical skills. These are to be answered in brief

Questions
SECTION-A

Question 1.
Define saturated solution.

Question 2.
What is plasma membrane made up of?

Question 3.
What would happen to the cell if there is no Golgi apparatus?

Question 4.
During free fall what is the weight of the body? Give reasons for the answer.

Question 5.
The relative density of gold is 19.3. The density of water is 10³ kg/m³? What is the density of gold in S.I. unit?

Question 6.
Two block pieces of same mass and same size are dipped in water and oil. One block floats in water and the other sinks in oil. Explain why? When you mix oil and water, explain what .will be the top layer of the mixture.

Question 7.
Write the electronic configuration and valency of the following:

1. Fluorine
2. Potassium
3. Silicon

OR
You are given an element \(_{ 17 }^{ 35 }{ X }\) .

1. Find the number of protons, electrons and neutrons.
2. Valency of X.
3. Write the chemical formula of the compound formed when it combines with carbon and sodium.

Question 8.
Why is ice at 273 K more effective in cooling than water at the same temperature?
OR
How would you confirm that a colourless liquid given to you is pure water? Give three tests.

Question 9.
Give the function of the following: nuclear membrane, mitochondria, ribosomes.

Question 10.
Classify the following animals into their phyla giving, one reason:

1. Earthworm
2. Scorpion
3. Starfish

Question 11.
Deine by drawing the graphs to show the following:
(a) Uniform acceleration
(b) Non-uniform acceleration
(c) Uniform motion

Question 12.

1. Define atomic mass unit.
2. Distinguish between molecular mass and molar mass.
3. Deine and give one example of
   • diatomic and
   • triatomic molecule of compounds.

Question 13.

1. Explain why it is dangerous to jump out of a moving bus.
2. Explain why a sportsman gives a swing to his arm while catching a cricket ball.
3. How does a karate player break a slab of ice with a single blow.

Question 14.
A radio station is transmitting its signals at a frequency cf 400 MHz. If the velocity of radio wave is 3 × 10⁸ m/s, calculate the wavelength of radio waves.

Question 15.
Define power. Write is its S.I. unit. An electric bulb is rated 15 watts. What does it mean? What is the energy consumed in joules if it is used for 10 minutes?

Question 16.
The velocity time graph of a body is given as follows:

(i) State the kind of motion represented by OA; AB.
(ii) What is the velocity of the body after 10 s and after 40 s?
(iii) Calculate the retardation of the body.
(iv) Calculate the distance covered by the body between 10th and 30th second.

Question 17.

1. Define vaccine. Name two vaccines given to the children.
2. What is antibiotic penicillin? Give its function.

Question 18.
How can crop variety improvement methods come to the rescue of farmers facing repeated crop failures? Describe three factors for which they could do crop improvement.
Which is the most common method of obtaining improved variety of crops? Explain briefly.

Question 19.
Explain ‘potential energy’ in your own words and give an example of it. State the S.I. unit of potential energy. Write the expression for the potential energy of an object of mass ‘m’ that has been raised to a height ‘h’ from the ground.
A body of mass 20 kg is lifted up by 10 meters. Calculate its potential energy. If this body is allowed to fall freely, find its kinetic energy just before it touches the ground. (Take g= 10 m/s²)

Question 20.
(a) Distinguish between true solution, suspension and colloids in a tabular form under the following headings:
(i) Stability
(ii) Filterability
(iii) Type of mixture
(b) What is meant by concentration of a solution? How will you prepare a 10% solution of glucose in water?

Question 21.

1. State one similarity and one difference between evaporation and boiling.
2. List four factors which affect the rate of evaporation.
3. Describe an activity to show that water vapour is present in air.

SECTION-B

Question 22.
Four measuring cylinders with different least counts are shown in figures A, B, C and D. Name the most suitable cylinder for determining the volume of a cube of side 1 cm and why?

Question 23.
A teacher soaked 10 raisins in 35 mL of distilled water in a beaker labelled A and perform a similar activity and label the other beaker B. She maintained the temperature of beaker A at 20°C and B at 40°C. After an hour which one has higher percentage of water absorbed by raisins, beaker A or by those in beaker B?

Question 24.
Three students A, B and C determined the volume of a solid by immersing it in water in the overflow cans set-up as shown.

In which of these cases the result obtained will be correct/incorrect and why?

Question 25.
How does a cockroach adapt itself to wide range of habitats?

Question 26.
What are the different adulterants commonly used in foods?

Question 27.
Two bottles of equal volume are filled with glycerin and water respectively. Which of the bottle will be heavier? Give reason for your answer.

Answers
SECTION-A

Answer 1.
The solution in which no more solute can be dissolved at given temperature.

Answer 2.
Prateins and Lipids

Answer 3.
Golgi apparatus has the function of storage, modification and packaging of the products in vesicles. If there were no Golgi bodies, packaging and dispatching of materials synthesised by the cell will be stocked and it remained unclear where the proteins or synthesised materials will go.

Answer 4.
No weight, as the body is experiencing the force due to gravity.

Answer 5.
Relative density of gold = 19.3
Relative density of gold = \(\frac { Densityofgold }{ Densityofwater }\)
∴ Density of gold = Relative density of gold × Density of water
= 19.3 × 10³ kg/m³
= 19300 kg/m³

Answer 6.
The density of water is more than oil. Hence the buoyant force exerted by water on the object is more than by oil. Therefore among two identical pieces, one piece will float in water and the other sinks in oil.
Oil will float on water as its density is less than water. Therefore, oil will form the topmost layer.

Answer 7.

1. Flourine: Atomic number = 9; Electronic configuration = 2,1 and Valency = 1
2. Potassium: Atomic number = 19; Electronic configuration = 2, 8, 8, 1 and Valency = -1
3. Silicon: Atomic number = 14; Electronic configuration = 2, 8, 4 and Valency = 4

OR

1. Protons = 17, Electrons = 17 and Neutrons = 35 – 17 = 18
2. Valency of X is 1.
3. CX₄ and NaX

Answer 8.
At 273 K or 0°C, ice will have more cooling than water because it can absorb more heat than water due to its latent heat of fusion. Water at the same temperature does not hold the latent heat of fusion, that is the hidden heat which is present in ice and thus it cannot absorb heat more than ice and will have less cooling effect.
OR

• Boiling test of water: Pure water has fixed boiling point of 100 degree Celsius. If a liquid boils at this temperature, then it is water.
• On boiling a sample of water all the water should evaporate and nothing is left behind, no salt or residue.
• pH test and freezing point: The pH of water is 7, freezing point of water is 0 degree Celsius. If a liquid freezes at 0 degrees, then it is water.

Answer 9.

• Nuclear membrane: It is a membrane made up of double layer of lipid and it is also called as the envelope that protects the nucleus in the cell.
• Mitochondria: It is called the powerhouse of the cell as it stores energy in the form of ATP. It regulates the metabolism.
• Ribosomes: It helps in making of proteins in the cell. Protein is needed for many cell functions such as repairing, damage or directing the chemical processes.

Answer 10.

1. Earthworm: Annelids, as their body is segmented.
2. Scorpion: Arthropoda, as it has joint appendages.
3. Starfish: Echinodermata, as it has calcareous skeleton and tube feet.

Answer 11.

Answer 12.

1. Atomic mass unit: A unit of mass used to express atomic and molecular weights, equal to one twelfth of the mass of an atom of carbon-12 isotope.
2. Molecular mass: Molecular mass of a compound is the mass of of its one molecule. This is measured in atomic mass unit (amu). 1 atomic mass unit is the one twelfth of the mass of an atom of C-12 isotope. When the mass of a molecule is divided by the mass of one twelfth of the mass of an atom of C-12 isotope, its relative mass is obtained.
   • Molar mass: This is also known as molecular weight. It is the mass of a substance for a given amount. The S.I. unit for the molar mass is g mol^-1. This gives the amount of the atoms/molecules/ions present in one mole of a substance.
3. • Diatomic molecule of compound: A molecule of a compund with two atoms, e.g. MgO, NaCl.
   • Triatomic molecule of compound: A molecule of a compound with three atoms, e.g. CO₂, H₂O.

Answer 13.

1. While moving in a bus our body is in the state of motion. On jumping out of a moving bus our feet touches the ground and came to rest, while the upper part of our body stays in motion and moves forward due to inertia of motion and hence we can fall in forward direction.
2. While catching a fast moving cricket ball, a fielder on the ground gradually pulls his hands backwards with the moving ball. This is done so as to increase the time during which the high velocity of the moving ball decreases to zero. Thus, the acceleration of the ball is decreased and so the impact of catching the fast moving ball is reduced.
3. A karate player applies the blow with a large velocity in a very short interval of time on the ice slab, which therefore exerts a large amount of force on it and suddenly breaks the ice slab.

Answer 14.
Frequency of the signals = 400 MHz
= 400 × 10⁶ Hz
Velocity of the waves = 3 × 10⁸ m/s
Wavelength of the radio waves = ?
We know, Speed = Wavelength × Frequency

Answer 15.
Power is the rate of doing work i.e. the amount of work done per unit time.
S.I. unit: Watt
If a bulb is rated 15 watts, it means it consumes 15 joules per second.
Therefore, power = \(\frac { Energy }{ Time }\)
So, Energy = Power × Time
Therefore energy consumed by the bulb is 15 × (10 × 60) seconds
= 15 × 600
= 9000 Joules

Answer 16.
(i) OA – uniform acceleration, AB – zero acceleration/constant velocity.
(ii) 20 ms^-1 : zero/body comes to rest.

(iv) Distance between 10th and 30th second = area of figure shaded
= (30 – 10)s × 20 ms^-1
= 20 s × 20 m s
= 400 m

Answer 17.

1. Vaccine is a chemical/drug given in advance to an individual to give immunity to the body against certain diseases.
   Two vaccines given to children are:
   • BCG – for tuberculosis prevention
   • Polio drops – for polio prevention
2. Penicillin is an antibiotic that blocks the bacterial processes to build the cell wall. Due to this drug, the bacteria is unable to make a protective cell wall and dies easily. It is used to cure the diseases and infections caused by bacteria.

Answer 18.
Crop variety improvement methods came to the rescue of the farmers, facing repeated crop failures in the following ways:

1. Improved quality of crops are obtained in higher yield.
2. The cost of production is reduced & there is uniform maturity of crops which makes harvesting process easier & reduces loss during harvesting.
3. Crops with desirable agronomic characteristics are obtained having wider adability to the climatic conditions.
4. Soil fertility is maintained and there is no or minimum weeds.

Three factors for which farmers can do crop variety improvement are:

1. Develop biotic and abiotic resistance
2. Wider adaptability
3. Early and uniform maturity

Most common method is Hybridisation, which involves crossing between two varieties having genes for the desired characteristics and bringing them together into a new variety called the hybrid.

Answer 19.
‘Energy possessed by an object by virtue of its position or configuration. ’ (To be explained in candidate’s own words.)
Example: Stretched string of bow/ a stone lifted to a certain height (or any other appropriate example).
S.I. unit – Joule
Potential Energy, PE. = mgh
As the object falls, m = 20 kg g = 10 m/s² h = 10 m
∴ P.E = mgh
= 20 kg × 10 m/s² × 10 m
P.E = 2000 J
Its P. E. gets converted to K. E.
Kinetic energy just before it touches = 2000 J

Answer 20.
(a)

(b) Concentration of a solution is the amount of the solute present in a given amount (mass or volume) of solution (or solvent).
Dissolve 10 g or glucose in 100 g – 10 g = 90 g of water

Answer 21.
1. Similarity: Liquid state is changed into of a substance its gaseous state.

2. Four factors:

• Surface area of the liquid exposed to the atmosphere
• Temperature of the liquid
• Humidity
• Wind velocity
• Vapour pressure of the liquid (any four)

3. When ice cold water or crushed ice is taken in a tumbler, water droplets soon appears on the outer surface of the tumbler./Anhydrous calcium chloride turns wet on keeping exposed to air. (Any one)

SECTION-B

Answer 22.
Cylinder A with the minimum least count will be used to find the volume of a cube with very small dimensions.

Answer 23.
The raisins soaked in B will have absorbed more water as the temperature of water is higher and as the osmosis process will be more in B than in A, since the temperature of water in A is less.

Answer 24.
In all the three cases the result obtained will be incorrect. This is because the water in the overflow can should be filled upto the outlet brim.

Answer 25.
Cockroach has a hard exoskeleton that serves many functions, including protection from water loss and physical injury and internally aids in muscle attachment, which results in tremendous leverage and strength. It also undergoes hibernation during unfavourable conditions.

Answer 26.
The commonly used adulterants in food are:

• Black pepper: dry seeds of papaya
• Honey: jaggery
• Red chilli powder: red brick powder
• Mustard seed: argemone seeds

Answer 27.
The bottle with glycerine would be heavier because its mass is greater than water. The density of a substance is directly proportional to the mass of the body. The density of glycerine is 1.26 g/cc and that of water is 1 g/cc.

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CBSE Sample Papers for Class 9 Science Paper 6 are part of CBSE Sample Papers for Class 9 Science. Here we have given CBSE Sample Papers for Class 9 Science Paper 6.

CBSE Sample Papers for Class 9 Science Paper 6

Students who are going to appear for CBSE Class 9 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 6 of Solved CBSE Sample Paper for Class 9 Science is given below with free PDF download solutions.

Time Allowed : 3 Hours
Max. Marks: 80

General Instructions

• The question paper comprises of two Sections, A and B. You are to attempt both the sections.
• All questions are compulsory. However an internal choice will be provided in two questions of 3 marks each and one question of five marks.
• All questions of Section A and all questions of Section B are to be attempted separately.
• Question numbers 1 to 2 in Section A are one-mark questions. These are to be answered in one word or in one sentence.
• Question numbers 3 to 5 in Section A are two-marks questions. These are to be answered in about 30 words each.
• Question numbers 6 to 15 in Section A are three-marks questions. These are to be answered in about 50 words each.
• Question numbers 16 to 21 in Section A are five-marks questions. These are to be answered in about 70 words each.
• Question numbers 22 to 27 in Section B are two-marks questions based on practical skills. These are to be answered in brief

Questions
SECTION-A

Question 1.
Convert the following into Celsius scale: 300 K and 573 K

Question 2.
An organism does not have a well defined nucleus and organelles. State its kingdom.

Question 3.
Name the compounds whose formulae are given below:

1. Ca(OH)₂
2. KMnO₄

Question 4.
Differentiate between infectious and non-infectious diseases.

Question 5.
Calculate the number of moles present in 60 gm of calcium.

Question 6.
State the law of constant proportion. Illustrate it with examples.

Question 7.
What is ultrasound? Give two uses of ultrasound.

Question 8.

1. Define atomic mass unit.
2. Write the chemical formula for potassium oxide and ammonium chloride.

Question 9.
A man is suffering from AIDS.

1. What is the cause of AIDS and give its full form.
2. Write two ways by which this disease gets transmitted.
3. State any one precaution for prevention of AIDS.

OR
Define the term “symbiosis”. Name a symbiotic life forms. Name the place where these life forms are found.

Question 10.
Distinguish between density and relative density of a substance. The relative density of silver is 10.8. If the density of water is 10³ Kg/m³ find the density of silver.

Question 11.
Differentiate between radial symmetry and bilateral symmetry. Give one example of organism having this symmetry for each.

Question 12.

1. State Archimedes principle.
2. State the laws of floatation.
3. Why is it easier to swim in sea water than in river water.

OR
State Pascal’s law for pressure. Why tip of pin is sharp but the head is broad? How camels walk easily in desert soil.

Question 13.
Explain the Rutherford’s model of atom. Write his three observations and conclusions made by alpha particle splitting experiment.

Question 14.
Calculate the atomic mass of chlorine if it exists commonly in the form of two isotope. Cl mass number 35 – 75%, Cl mass number 37 – 25%. Name two isotopes which can cure diseases.

Question 15.
What are the different means by which infectious diseases are spread?

Question 16.
(a) Explain the various factors on which the rate of evaporation depends, giving example.
(b) Explain how the high compressibility of gases is useful.

Question 17.
How can you separate the following mixture:

1. Sand + iron
2. Cream from milk
3. Salt + water
4. Ammonium chloride + NaCl
5. Copper sulphate and water
6. Rice and dal (uncooked)
7. Gases from air
8. Petrol and diesel form crude oil
9. Drugs from blood
10. Acetone from water

Question 18.
(a) What is uniform circular motion?

(b) An athlete runs on a circular track, whose radius is 50 m with a constant speed. It takes 50 seconds to reach point B from starting point A. Find
(i) the distance covered
(ii) the displacement
(iii) the speed.

Question 19.
(a) Describe on activity to obtain crystals of copper sulphate from its solution.
(b) Draw a flow chart to show the water purification system. Why is chlorination of water important?

Question 20.
What is a disease? How do you know if a person has got disease? List various causes for the disease.

Question 21.
Explain the physical, chemical and biological factors which lead to the formation of soil.
OR
Explain nitrogen-cycle in nature and define all the terms involved in it.

SECTION-B

Question 22.
Some raisins weighed 10 g before they were placed in water for four hours. The raisins were then removed, wiped and weighed again. Their weight was found to be 12.5 g. Calculate the percentage of water imbibed by them.

Question 23.
The given diagram shows the stage of mosquito,

Give the name of this stage state two significant characteristics.

Question 24.
A student studied the different parts of seed. Lable the parts of seed studied by him.

Question 25.
Why does the temperature remain unchanged until the entire solid changes into liquid even if we are heating the solid?

Question 26.
A rectangular body has dimensions x and y (l and b). If its dimensions get doubled what will happen to its volume?

Question 27.
If in the first step the mixture consisting of sand, common salt and NH₄Cl had been dissolved in water what would have been the difficulty in separation?

Answers
SECTION-A

Answer 1.
300 K = 27 degree Celsius
573 K = 300 degree Celsius

Answer 2.
Monera

Answer 3.

1. Calcium Hydroxide
2. Potassium permanganate or Potassium manganite.

Answer 4.

Answer 5.
Given mass, m = 60 g
Molar mass, M=40 g mol^-1
No. of moles, n= \(\frac { m }{ M } \) = \(\frac { 60 }{ 40 } \) = 1.5 mol

Answer 6.
Law of constant proportion states that ‘a chemical compound is always made up of the same elements combined together in the fixed proportion by mass’.

Water is composed of hydrogen and oxygen combined together in the ratio 1:8 by weight.
Atomic mass of hydrogen = 2, Atomic mass of oxygen = 16, when they combine,
∴ Ratio = \(\frac { 2 }{ 16 } \) = \(\frac { 1 }{ 8 } \) = 1 : 8
In water (H₂O) the ratio of hydrogen to oxygen is 1 : 8 in which 1 g of hydrogen and 8 g of oxygen is needed to form the compound (H₂O).
Similarly in ammonia, the ratio of nitrogen to hydrogen is 14 : 3.

Answer 7.
Ultrasound is the name given to the sound waves that have frequencies greater than 20000 Hz.
Uses of Ultrasound:

• Checking the growth of a foetus.
• Breaking down kidney stones and stones elsewhere in the body.
• Measuring the speed of blood flow in the body. (Any two)

Answer 8.

1. The atomic mass unit is a unit used to express the atomic mass of atoms and molecular masses of compounds. One atomic mass unit is a mass unit exactly one twelfth of the mass of one atom of Carbon-12.
2. K₂O and AlCl₃

Answer 9.

1. AIDS is caused by HIV virus, its full form Acquired Immuno Deficiency Syndrome.
2. It can be transmitted from an is infected person to another person by use of common syringe, through sexual contact etc.
3. Use of disposable syringes test before blood transfusion.

OR
Symbiosis is a relationship in which two organisms are associated and are mutually benefited. Lichen is an example of symbiotic life form. These life forms are found in pollution free environment, e.g. on the tree trunks, rocks, ground etc.

Answer 10.

Relative density of silver =10.8
Density of water = 10³ kg m^-3
∴ RD = \(\frac { Densityofsilver }{ Densityofwater } \)
Density of silver = RD × Density of water
= 10.8 × 10³ kg m^-3

Answer 11.

Answer 12.

1. Archimedes Principle: a body totally or partially immersed in a fluid is subject to an upward force equal in magnitude to the weight of fluid it displaces.
2. • A freely floating body in a fluid displaces the weight of the fluid equivalent to its own weight.
   • The centre of gravity of the freely floating body and the centre of gravity of the fluid are in the same vertical line,.
3. It is easier to swim in the sea water because it is denser than the river water and thus it can exerts more upthrust.

OR
Pascal’s law or tile principle of transmission of fluid-pressure states that “pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all the directions throughout the fluid such that the pressure ratio (initial difference) remains same”.
The tip of the pin can be easily pierced into the cloth with less pressure exerted on the smaller area for larger impact.

Camel’s feet are broad and larger area of the feet reduces the force/pressure exerted by the body on the sand. But when we have to walk on the same sand, we sink because the pressure exerted by our body is not distributed, but it is directional.

Answer 13.
Rutherford’s α-particle scattering experiment:
Fast moving α-particles were made to fall on a thin gold foil. These particles have + 2 charge and 4 u mass, and have considerable amount of energy. When they hit the gold foil the following observations are made:

• Most of the a-particles passed straight through the foil.
• Some of the a-particles were deflected by small angles through the foil.
• One out of every 20,000 particles were rebounded.

Conclusion:

1. Most of the space inside the foil is empty.
2. Positive charge of the atom occupies very less space.
3. Mass of the atom is concentrated in the centre of the atom with all positive charge concentrated in the small volume within the atom.

Answer 14.
Average atomic mass = \(\frac { 75 }{ 100 } \) × 35 + \(\frac { 25 }{ 100 } \) × 37
=26.25 + 9.25 = 35.5 u
Cobalt-60 is used to cure cancer and Iodine-123 is used for thyroid treatment.

Answer 15.
The different means by which infectious diseases spread are:

1. Through air: They are also called airborne diseases. Air carries bacteria, virus and the diseases that can be caused are common cold, influenza, tuberculosis etc.
2. Throujfn food and water: When one eats/drink contaminated food/water, that contains bacteria, virus, worms etc, it can cause diseases like cholera typhoid, hepatitis.
3. Through contact: Many diseases spread by contact of an infected person with the healthy person. Example, fungal infections, skin diseases, etc.
4. By sexual contact: Many diseases can be transmitted through sexual contact. Example, syphilis, AIDS.
5. By body fluids: Fluids like blood, semen, mother’s milk when infected can also cause diseases. Example, AIDS.
6. Vectors: The organisms that spreads diseases by carrying pathogens from one place to another are called vectors. Example, mosquitoes are vectors that carry pathogens like protozoa.

Answer 16.
(a) The rate of evaporation depends on the following factors:

1. Surface area: If the surface area is increased the rate of evaporation also increases.
   • To dry the clothes faster we spread them to dry.
   • Tea in a saucer cools faster than in a cup.
2. Temperature: If the temperature is increased the rate of evaporation also increases. Due to increase in temperature the particles gain more kinetic energy and the phase changes from liquid to gaseous phase, e.g. water will evaporate faster in the presence of sun than in shade.
3. Humidity: It is the amount of water vapour present in air. The air can hold definite amount of water vapour, at a given temperature. If the amount of water vapour is high in the air then the rate of evaporation decreases.
   On a hot and humid day, desert coolers are not effective as the air cannot hold anymore moisture to get the cooling effect.
4. Wind speed: With increase in wind speed, the rate of evaporation increases.
   The particles of water vapour moves away with the wind, thereby decreasing the amount of water vapour in the surroundings.

(b) Gases have high compressibility. This property is used in the following situations:

1. LPG (liquefied petroleum gas) is a fuel which is made up of petroleum gas. On compressing this liquified petroleum gas, it forms liquid. Similarly CNG, i.e. compressed natural gas is used as a fuel in vehicles and at home.
2. Oxygen cylinders in the hospitals have compressed gas filled in it.

Answer 17.

1. Magnetic separation
2. Centrifugation
3. Evaporation
4. Sublimation
5. Crystallisation
6. Hand picking
7. Distillation
8. Fractional distillation
9. Chromatography
10. Distillation

Answer 18.
(a) When a body moves in a circular path with uniform speed, its motion is called uniform Circular motion.

Answer 19.
(a) Activity demonstrating preparation of crystals of copper sulphate from its solution:

• Take a clean beaker (250 mL) and put the copper sulphate solution in it.
• Heat the solution in the beaker to 60 – 70° C with continuous stirring, on a wire gauze.
• Filter the solution and collect the filtrate in a china dish.
• Place the china dish over the wire gauze placed over a tripod stand and heat it gently (do not boil).
• As the solution gets heated, stir it using a glass rod. This helps in uniform evaporation and also prevents the formation of solid crust.
• When the solution is reduced to one-half of is volume, take out a drop of the concentrated solution from one end of the glass rod and cool it by blowing air. Formation of thin crust indicates that crystallisation point is achieved.
• Turn off the burner, cover the dish with a watch glass, and keep it undisturbed. As the solution cools down, crystals will separate out. Slow cooling ensures better crystallisation.
• Decant the mother liquor and wash the crystals with a thin stream of cold water and dry the crystals by pressing them gently between the sheets of filer paper.
• Blue coloured crystals of copper sulphate (CuSO₄ . 5H₂O) are formed).

Chlorination of water helps to check the growth of disease causing microbes, e.g. bateria, protozoa, etc. and it thus helps in preventing waterborne diseases. Thus, chlorination of water is important.

Answer 20.
Disease is a condition in which an individual suffers from one or more type of illness/ is not in the state of being called as healthy.
Common methods of transmission of diseases:

The common methods of transmission of diseases are:

• By air – cough, cold, tuberculosis
• By food and water – typhoid, jaundice
• By mosquito bite – malaria
• By rabid animal – rabies
• By direct contact – skin infection, small pox, AIDS
• By indirect contact – typhoid, chicken-pox

Answer 21.
Physical factors:

• Wind: When the wind blows it erodes big rocks which rub and hit with the other rocks breaking into smaller pieces which are further carried by wind to form soil.
• Sun: The heat of sun causes expansion of the rocks due to heating during daytime and it contracts at night. This expansion and contraction causes cracks in the rocks, which breaks slowly to form soil.
• Water: When it rains the force of rain water erodes the rocks which breaks to form soil.
  At times this water enters the cracks present in the rocks and freezes when temperature falls which breaks the rocks to forms soil.

Chemical factors:

• Water: Water when reacts with carbonates and phosphates present in the rocks, it form soluble compounds which make the rock hollow from inside.
• Biological factor: Living organisms also help in the formation of soil. The lichen that grows on moist surface of rocks releases certain substances that causes the rock surface to powder down and form thin layer of soil. Other small plant like moss are able to grow on this surface now.
  The roots of big trees sometimes go into cracks in the rocks and when the tree grows bigger the crack in the rocks is forced bigger.

OR
Terms involved in nitrogen-cycle are:

1. Nitrogen fixation: Plants cannot use free nitrogen present in the air. This nitrogen molecule is converted into nitrates and nitrites which can be taken up and used to make the required molecule.
   This is called nitrogen fixation which can be done by the bacteria that live in the root nodules of leguminous plants.
2. Nitrification: By physical process, i.e. during lightning, the high temperature and pressure created in the air convert nitrogen into oxides of nitrogen which dissolves in water and came down along with rain. This is also called nitrification.
3. Ammonification: The nitrogen compounds formed are taken by plants to form proteins which are further converted into ammonia.
4. Denitrification: The nitrates and nitrites of nitrogen are acted upon by other group of microbes e.g. Pseudomonas bacteria, which convert these compounds into free nitrogen gas.

Nitrogen cycle:

1. Free nitrogen from atmosphere is converted into nitrates by bacteria or by lightning.
2. Nitrates mix with soil, is absorbed by the plants to make proteins.
3. The proteins in plants and animals are converted into amino acids and ammonia.
4. Ammonia is converted into nitrates and then these nitrates and nitrites present in soil is acted upon by other group of bacteria called denitrifying bacteria. This process is called denitrification.
5. Nitrates are converted into free nitrogen and is released back to the atmosphere.

SECTION-B

Answer 22.
Weight of raisins (x) = 10 g
Weight of swollen raisins (y) = 12.5 g
The percentage of water absorbed by the raisins = \(\frac { y-x }{ x } \) × 100
= \(\frac { 12.5 – 10 }{ 10 } \) × 100 = 25%

Answer 23.
This stage is called Tumblers.
The significant characteristics are it floats on water and takes oxygen through he tube named trumpets. This is the hibernating stage.

Answer 24.

• A – seed-coat
• B – cotyledon

Answer 25.
The temperature remains unchanged until the entire solid changes into liquid even if we are heating the solid; it is because the heat is used up by the molecules in overcoming the forces of attraction between the parcticles of the solid.

Answer 26.
Suppose the dimensions of a rectangular solid is 1 then
V = 1 × 1 × 1 × (l × b × h taken as 1)
V= 1³
If it is doubled, then V = 2³
V = 8 times
Hence volume will increase by 8 times.

Answer 27.
The mixture given for separation is sand, common salt and ammonium chloride. The later two (i.e., common salt and ammonium chloride) dissolves in water. If the mixture had been dissolved in water in the first step, then the separation of these constituents would be a difficult task.

We hope the CBSE Sample Papers for Class 9 Science Paper 6 help you. If you have any query regarding CBSE Sample Papers for Class 9 Science Paper 6, drop a comment below and we will get back to you at the earliest.

CBSE Sample Papers for Class 9 Science Paper 5 are part of CBSE Sample Papers for Class 9 Science. Here we have given CBSE Sample Papers for Class 9 Science Paper 5.

CBSE Sample Papers for Class 9 Science Paper 5

Students who are going to appear for CBSE Class 9 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 5 of Solved CBSE Sample Paper for Class 9 Science is given below with free PDF download solutions.

Time Allowed : 3 Hours
Max. Marks: 80

General Instructions

• The question paper comprises of two Sections, A and B. You are to attempt both the sections.
• All questions are compulsory. However an internal choice will be provided in two questions of 3 marks each and one question of five marks.
• All questions of Section A and all questions of Section B are to be attempted separately.
• Question numbers 1 to 2 in Section A are one-mark questions. These are to be answered in one word or in one sentence.
• Question numbers 3 to 5 in Section A are two-marks questions. These are to be answered in about 30 words each.
• Question numbers 6 to 15 in Section A are three-marks questions. These are to be answered in about 50 words each.
• Question numbers 16 to 21 in Section A are five-marks questions. These are to be answered in about 70 words each.
• Question numbers 22 to 27 in Section B are two-marks questions based on practical skills. These are to be answered in brief

Questions
SECTION-A

Question 1.
Why is evaporation called a surface phenomenon?

Question 2.
Kingdom Fungi have cell wall but it is not classified under kingdom Plantae. Give reason.

Question 3.
What is chromatography? Give its one application.

Question 4.
What are isotopes and isobars?

Question 5.
What is the commercial unit of energy? Define it.

Question 6.
Name the Italian bee variety commonly used for commercial honey production. What are the qualities of this bee which makes it most suitable?

Question 7.
Which separation technique is used to separate the following:

1. Cream from milk
2. Oil from ester
3. Camphor from mixture containing camphor and sodium chloride

Question 8.
Explain why:

1. Lysosomes are known as suicidal bags.
2. Mitochondria are known as powerhouse of the cell

OR
What are ribososmes? Where are they located in the cell? What is their function?

Question 9.
Why is excess use of fertilisers harmful for environment?

Question 10.
If bromine atom is available in the form of two isotopes say \(_{ 35 }^{ 79 }{ Br }\) (49.7%) and \(_{ 35 }^{ 81 }{ Br }\) (50.3%), calculate the average atomic mass of bromine atom.

Question 11.
What is AIDS? How does a person get affected with HIV?

Question 12.
A boy possess potential energy of 460 J whose mass is 20 kg and is raised to a certain height.
What is the height. [Take g = 10m/s²]
OR
A car accelerates uniformly from 20 km/h to 35 km/h in 5 s. Calculate
(i) the acceleration and
(ii) the distance covered by the car in that time?

Question 13.

1. Under which category of mixtures will you classify alloys and why?
2. A solution is always a liquid. Comment.
3. Can a solution be heterogeneous? Justify.

Question 14.
Establish the relationship between speed, wavelength and frequency of sound waves.

Question 15.
What is acid-rain? Give its harmful effects.

Question 16.
Explain Rutherford’s a-particle scattering experiment and give its observation and conclusion drawn from the experiment.

Question 17.
Represent graphically:
(a) Two sound waves having same amplitude but different frequencies.
(b) Two sound waves having different amplitudes and also different wavelengths.
(c) Two sound waves having same frequency but different amplitude.
(d) Also write the characteristic of sound obtained.

Question 18.
Explain different types of fisheries.

Question 19.
State Archimedes principle. State laws of floatation. Explain why iron nail sinks but iron boat floats. Why is it easier to swim in sea water than in river water?

Question 20.

1. How carbon exists in nature?
2. Explain the carbon-cycle in nature.

OR
Explain nitrogen-cycle in nature and define all the terms involved in it.

Question 21.
Explain with examples:

1. Atomic number
2. Mass number
3. Isotopes
4. Isobars

Give any two uses of isotopes.

SECTION-B

Question 22.
The water level in a measuring cylinder, before and after immersing a metal cube in it, is shown in the figure. Calculate the volume of the metal cube.

Question 23.
What would happen when zinc granules are added to dilute sulphuric acid in a test tube? Record any two observations.

Question 24.
Which experimental set-up is correct for determining the melting point of ice? Why?

Question 25.
You can bite fruits like guava, grapes, banana etc., but not a piece of wood. Why?

Question 26.
Why does brass react with dilute hydrochloric acid and is corroded in rainy season to form CuCO₃ . CU(OH)₂?

Question 27.
State the life span of each stage of mosquito.

Answers
SECTION-A

Answer 1.
The water molecules at the surface gains heat energy, required to convert liquid water into vapours, hence it is called a surface phenomenon.

Answer 2.
Fungi does not have chloroplast to prepare its own food.

Answer 3.
It is a separating technique of two or more coloured mixtures or colourless mixtures. It can also be used to detect the impurities present in coloured food items.

Answer 4.

• Isotopes: Atoms of the same element with same atomic number but different mass number.
• Isobars: Atoms of diferrent elements with same mass number but different atomic number.

Answer 5.
k W h. When 1000 watt is used for one hour it is called 1 kW h.

Answer 6.
Apis Mellifera is commonly used bee.
The bee is stingless, produces more honey and lives at a single place for a long time.

Answer 7.

1. Centrifugation
2. Distillation
3. Sublimation

Answer 8.

1. Lysosomes helps to keep the cell clean by digesting out foreign waste materials and worn out cells (or cell organelles) with the help of powerful digestive enzymes that it contains. It can worn out the entire cell & burst out and thus known as suicidal bags of the cell.
2. Mitochondria stores energy in the form of ATP molecules and provides the energy when needed by the cell. Hence, it is called the powerhouse of the cell.

OR
Ribosomes are spherical organelles present in the cell which are either freely distributed in the cytoplasm or may be attached to the endoplasmic reticulum. It consists of ribosomal RNA (Ribonucleic acid) and proteins.
Functions of Ribosomes: It helps in the synthesis of proteins.

Answer 9.
It changes the nature of the soil.
It lowers the water holding capacity of soil.
The chemical enters the food chain, as it is an inorganic chemical and not used by animals, so it gets accumulated in the top most consumers leading to biological magnification and can cause various harmful diseases like cancer.

Answer 10.
The average atomic mass of bromine atom

Answer 11.
AIDS means Acquired Immuno Deficiency Syndrome, which is caused due to HIV- human immuno deficiency virus. This virus reduces the immunity of the human body. Therefore if any pathogen enters the body of a person and causes any disease then it can kill the person. The virus is transmitted from an infected person to person by any of the following ways:

• Blood transfusion
• From mother (infected) to the baby in the womb
• From the infected mother’s milk to the lactating baby
• By sexual contact
• Sharing Reusing a needle used by an infected person

Answer 12.
P.E. = 460 J, m = 20 kg, g = 10 m/s²
h= ?
P.E. = mgh
460 = 20 × 10 × h
h = \(\frac { 460 }{ 20\times 10 } \)
h = 2.3 m
The height at which the object is raised from the ground is 2.3 m.
OR

Answer 13.

1. Alloys are homogeneous mixtures as its constituents cannot be easily distinguished and have a uniform composition throughout.
2. A solution is obtained when a solute (solid/liquid or gas) dissolves in a solvent. Generally, the solvent is a liquid, such solutions are called liquid solutions. However, it is not necessary that a solution is always a liquid.
3. No, a solution cannot be heterogeneous as formation of a solution involves dissolving process, which always results in a homogeneous mixture.

Answer 14.
Speed of sound waves → The distance travelled by a sound wave or a point on a wave (compression or rarefaction) per unit time.

Where, X is wavelength of the sound wave and it is equal to the distance travelled by the sound wave in one time period (T) of the wave.

Speed = Wavelength × Frequency

Answer 15.
The harmful gases released due to combustion of fossil fuels are SO₂, NO₂, CO₂, these gases remain suspended in the air. When it rains the rain water mixes with these gases to form sulphuric acid, nitrous acid, carbonic acid and comes down on the surface of the earth in the form of acid-rain.
Harmful effects of acid-rain:

• It corrodes statues, monuments of marble, building etc.
• It makes the soil acidic.
• It damages crops, plants.

Answer 16.
Rutherford’s α-particle scattering experiment:
Fast moving α-particles were made to fall on a thin gold foil. Particles have + 2 charge, 4 u mass and considerable amount of energy when hits the gold foil, following observations are made:

• Most of the α-particles passed straight through the foil without any deflection.
• Some of the α-particles were deflected by small angles through the foil.
• One out of every 20,000 particles were rebounded.

Conclusion:

• Most of the space inside the atom is empty.
• Mass of the atom is concentrated in the centre which is positively charged in a small volume within the atom.
• The positively charged centre of atom is called the nucleaus of the atom.

Answer 17.

(d)

• Soft Sound
• Louder Sound

Answer 18.
The different types of fisheries are as follow:

• Marine fisheries: Marine fishes are caught using fishing nets. Large schools of fishes are located by satellites. Some are farmed in sea water.
• Mariculture: Marine fishes are cultured in sea water. This culture of fisheries is called mariculture.
• Inland fisheries: The fisheries done in fresh water resources like canals, ponds, reservoirs and rivers is called inland fisheries
• Capture fishing: It is done in sea water, estuaries and lagoons.
• Aquaculture: Culture of fishes done in different water bodies is called aquaculture.

Answer 19.
Archimedes Principle: When a body is immersed in a fluid (fully or partially), it experiences an upward force which is equal to the weight of the fluid displaced by it.
Law of Floatation:

• A freely floating body in a fluid displaces the weight of the fluid equivalent to its own weight.
• For a freely floating body, the centre of gravity of the floating body and the centre of gravity of the fluid in which it floats are in the same vertical line.

An iron nail sinks due to its high density and less buyoant force acting on the nail, while the iron boat floats because of more buyoant force acting due to increase in surface area.
It is easier to swim in sea water rather than river because the surface of sea water is more dense than river water and its is easier to float on a dense surface.

Answer 20.
1. Carbon exist in two different forms in nature-free and combined form.

• Free form: It occurs in the elemental form as diamond and graphite.
• Combined form: It occurs as carbon-dioxide, carbonate and hydrogen carbonate salts in various minerals. It is also present in proteins, carbohydrates, fats, nucleic acids and vitamins.

2. Carbon cycle:

• Carbon-dioxide present in the nature is used by the plants during photosynthesis to form glucose and carbohydrates.
• CO₂ dissolves in water to form carbonates, which forms limestone.
• Plants contain carbon in the form of glucose, carbohydrates, which are eaten up by the other animals.
• Animals form petroleum when submerged under the Earth and plants form coal. But if get decomposed after dying they release carbon back to the atmosphere by decomposition (dead) and respiration (living).

OR
Terms involved in nitrogen-cycle are

1. Nitrogen fixation: Plants cannot use free nitrogen present in the air. This nitrogen molecule is converted into nitrates and nitrites which can be taken up and used to make the required molecule. This is called nitrogen fixation, which can be done by the bacteria that live in the root nodules of leguminous plants.
2. Nitrification: By physical process i.e. during lightning, the high temperature and pressure created in the air converts nitrogen into oxides of nitrogen which dissolve in water and came down along with the rain. This is called nitrification.
3. Ammonification: The nitrogen compounds formed after nitrificaiton are taken by the plants to form proteins which are further converted into ammonia.
4. Denitrification: The nitrates and nitrites of nitrogen are acted upon by some group of microbes, e.g. Pseudomonas bacteria, which converts these compounds into free nitrogen gas.

Nitrogen cycle:

• Free nitrogen from atmosphere is converted into nitrates by bacteria or by lightning.
• Nitrates mixes with soil and is absorbed by the plants to make proteins.
• The proteins in plants and animals are converted into amino acids and ammonia.
• Ammonia is converted into nitrates and then these nitrates and nitrites present in soil is acted upon by a group of bacteria called denitrifying bacteria. This process is called denitrification. Nitrates are converted into free nitrogen and is released back to the atmosphere.

Answer 21.

1. Atomic number: The atomic number of an element is equal to the number of protons in the nucleus of its atom e.g., Oxygen has 6 protons hence atomic no. = 6. 1
2. Mass number: The mass number of an atom is equal to the number of protons and neutrons in its nucleus.
   Mass Number = Number of protons + Number of neutrons
3. Isotopes: Isotopes are the atoms of the same element which have different mass number but same atomic number, e.g., \(_{ 1 }^{ 1 }{ Br }\), \(_{ 1 }^{ 2 }{ Br }\), \(_{ 1 }^{ 3 }{ H }\)
4. Isobars: Isobars are atoms having the same mass number but different atomic numbers. e.g; \(_{ 20 }^{ 40 }{ Ca }\), \(_{ 18 }^{ 40 }{ Ar }\)
   Both calcium and argon have same mass number but different atomic number.

Two uses of isotopes are:

• An isotope of iodine is used in the treatment of goitre.
• An isotope of uranium is used as a fuel in nuclear reactors.

SECTION-B

Answer 22.
Initial volume of water = 40 cm³
Final volume of water after immersing the metal cube = 60 cm³
Volume of the metal cube = 60 – 40 = 20 cm³

Answer 23.

1. The bubbles/effervescence will be seen in the test tube and zinc granules will keep on disappearing.
2. The test tube will become warm.

Answer 24.
The set-up B is correct as the beaker contains crushed ice and the thermometer is in contact with the ice.

Answer 25.
The skin of fruits like apple, grapes guava is very soft and made up of soft tissues. On the other hand, the wood has many layers of dead cells which makes it hard.

Answer 26.
Brass is an alloy of copper and zinc. It is an homogeneous mixture. The combining elements retain their properties. Hence the copper in brass reacts with the carbonates in the air to form CuCO₃ . CU(OH)₂.

Answer 27.

We hope the CBSE Sample Papers for Class 9 Science Paper 5 help you. If you have any query regarding CBSE Sample Papers for Class 9 Science Paper 5, drop a comment below and we will get back to you at the earliest.

CBSE Sample Papers for Class 9 Science Paper 4 are part of CBSE Sample Papers for Class 9 Science. Here we have given CBSE Sample Papers for Class 9 Science Paper 4.

CBSE Sample Papers for Class 9 Science Paper 4

Students who are going to appear for CBSE Class 9 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 4 of Solved CBSE Sample Paper for Class 9 Science is given below with free PDF download solutions.

Time Allowed : 3 Hours
Max. Marks: 80

General Instructions

• The question paper comprises of two Sections, A and B. You are to attempt both the sections.
• All questions are compulsory. However an internal choice will be provided in two questions of 3 marks each and one question of five marks.
• All questions of Section A and all questions of Section B are to be attempted separately.
• Question numbers 1 to 2 in Section A are one-mark questions. These are to be answered in one word or in one sentence.
• Question numbers 3 to 5 in Section A are two-marks questions. These are to be answered in about 30 words each.
• Question numbers 6 to 15 in Section A are three-marks questions. These are to be answered in about 50 words each.
• Question numbers 16 to 21 in Section A are five-marks questions. These are to be answered in about 70 words each.
• Question numbers 22 to 27 in Section B are two-marks questions based on practical skills. These are to be answered in brief

Questions
SECTION-A

Question 1.
Define law of constant proportion.

Question 2.
State Newton’s Second law of Motion.

Question 3.
If one mole of carbon atoms weigh 12 g, what is the mass of 1 atom of carbon?

Question 4.
How is the process of diffusion in liquids different from that in solids?

Question 5.
Define energy. Name and define its S.I unit.

Question 6.
Calculate the number of atoms in 120 g of calcium and 120 g of iron. Which one has more number of atoms and how much is the difference?
(Given Atomic mass of calcium =40 u, Iron=56 u)

Question 7.
Define velocity and acceleration. Is it possible for a body to have a zero velocity but constant acceleration. Justify your answer.
OR
A boy drops a ball from a cliff 122.5 m high. Find :
(a) How long does it take the ball to fall to the ground?
(b) How far does it fall in the 1 st 3 seconds?
(c) How fast is it going at the end of 3 seconds?

Question 8.

1. Name the group of organisms which commonly cause infectious diseases.
2. Mention any two diseases that can be prevented by immunisation.

Question 9.
Explain the necessity of crop variety improvement in food production.
OR

1. What is the name of the competent plants that grows along with crops?
2. Why do farmers remove weeds from crop field?
3. Mention one control measure by which weeds can be destroyed.

Question 10.

1. A sound wave has a frequency of 2kHz and wavelength of 45 cm, it takes 4 seconds to travel. Calculate the distance it travels in 4 seconds?
2. If any explosion takes place at the bottom of the lake, what type of shock waves in the water will be produced.

Question 11.
Explain symbiosis and give an example.

Question 12.

1. Define Kinetic energy.
2. A stone of mass 2 kg is falling from rest from the top of a steep hill. What will be its kinetic energy after 5 sec? (g = 10 ms^-2)

Question 13.
A water tanker was completely filled with water. Abhishek saw the driver covering the mouth of the tanker with a lid. He immediately stopped the driver from doing so and told him that the tanker can lose balance while moving and can overtum/topple.

1. Why will the tanker overturn, if its lid is closed?
2. If the moving tanker with more than half-filled with water, applies sudden brake in which direction will the water fall.
3. What values of Abhishek is seen in the above case?

Question 14.
(a) A household consume 1 kW h of energy per day. How much energy is this in joules?
(b) A person carrying 10 bricks, each of mass 2.5 kg on his head moves to a height of 20 meter in 50 Seconds. Calculate the power spent in carrying bricks by the person? (g = 10 m/s²)

Question 15.
A body of mass 5 kg is thrown vertically upwards with a speed of 10 m/s, what is its kinetic energy when it is thrown? Find its potential energy when it reaches at the highest point. Also find the maximum height attained by the body. (g 10 m/s²)

Question 16.
Cite an experiment to show that sound needs a material medium for its propagation.

Question 17.
Why is AIDS considered to be a syndrome and not a disease?

Question 18.
Establish the relationship between speed of sound, its wavelength and frequency. If velocity of sound in air is 340 m/sec. Calculate the
(a) Wavelength when frequency is 256 Hz.
(b) Frequency when wavelength is 0.85 meter.

Question 19.
(a) What is uniform circular motion?
(b) An athlete runs on a circular track, whose radius is 50 m with a constant speed. It takes 50 seconds to reach the point B which is just opposite from the starting point A. Find

1. the distance covered
2. the displacement
3. the speed.

Question 20.
(a) Illustrate Rutherford’s experiment to explain the model of an atom.
(b) Atomic number of an element is 17. Identify the element, write its electronic configuration & mention its valency.
OR
Which separation technique you will apply for the separation of the following mixtures?

1. Oil from water.
2. Camphor from sand.
3. Sodium chloride from its solution in water.
4. Metal pieces from engine oil of a car.
5. Cream from milk.

Question 21.
Explain ‘potential energy’ in your own words and give an example of it. State the S.I. unit of potential energy. Derive an expression for potential energy of an object of mass ‘m’ that has been raised to a height ‘h’ from the ground.
A body of mass 20 kg is lifted up by 10 meters. Calculate its potential energy. If this body is allowed to fall, find its kinetic energy just before it touches the ground. (Take g = 10m/s²)

SECTION-B

Question 22.
The law of conservation of mass for the reaction between sodium bicarbonate and dilute hydrochloric acid can be verified only when it is carried in a closed container, explain why?

Question 23.
Biologists think that arthropoda are the most successful of all animals because of which feature?

Question 24.
State two precautions while measuring the volume of the cylinder.

Question 25.
What happens when dilute sulphuric acid is added to a compound of iron and sulphur?

Question 26.
In the reaction between copper sulphate and sodium sulphide solutions, when 15.9 g copper sulphate completely reacts with 7.8 g of sodium sulphide it is observed that 9.5 g of copper sulphide is formed. What is mass of sodium sulphate solution formed?

Question 27.
Name the stages in life cycle of mosquito.

Answers
SECTION-A

Answer 1.
In a chemical compound prepared by any method always contains the same elements in the fixed ratio by mass.

Answer 2.
The rate of change of momentum of an object is proportional to the applied unbalanced force directly in the direction of the applied force.

Answer 3.
1 mole of C = 12 g
1 mole of C = 6.022 × 10²³ Atoms
6.022 × 10²³ atoms of C = 12 g
1 Atom of C = \(\frac { { 12 } }{ { 6.022\times 10 }^{ 23 } }\)
= 1.99 x 10^-23 g

Answer 4.
The rate of diffusion in liquids is higher than that in solids because particles of liquids move freely.
Particles of liquids have larger intermolecular spaces than the particles in solid state.

Answer 5.
Energy is defined as the capacity of an object to do work. SI unit of energy is joule.
Energy possessed by a body is said to be 1 joule if it can displace an object by 1 m by applying a force of 1 N in the direction of force.

Answer 6.
1 mole of Ca = 40 g
No. of atoms of Calcium = No. of moles × 6.022 × 10²³

Answer 7.
Velocity: Rate of change of displacement.
Acceleration: Rate of change of velocity of a moving body.
When a body is released, its initial velocity, i.e. w = 0 but
g = 10m/s². Hence it is possible for a body to have zero velocity but constant acceleration.
OR

Answer 8.

1. Group of organisms causing infectious diseases are:
   • Virus
   • Bacteria
   • Fungi
   • Protozoa
   • Multicellular Worms
2. • Tetanus
   • Polio

Answer 9.

1. Higher yield
2. Improved quality
3. Biotic and abiotic resistance
4. Change in maturity duration
5. Desirable agronomic traits
6. Wider adaptability of crops (or any six relevant traits)

OR

1. Weeds. Example-Xanthium
2. They extract the nutrients from the soil that are meant for the crop plant.
3. By manual weeding or by applying weedicides.

Answer 10.

1. v = 330 ms^-1, t = 6 s
   D = \(\frac { vt }{ 2 }\) = \((\frac { 330\times 6 }{ 2 } )\) = 990 m
2. Longitudinal waves will be produced.

Answer 11.
Symbiosis refers to association between two organisms which benefit mutually from each other. Lichens is a symbiotic life form composed of algae and fungi.

Answer 12.

1. Energy due to the motion of a body is called kinetic energy.
   K.E = \(\frac { 1 }{ 2 }\) mv²
2. m = 2 Kg, t = 5 s
   Velocity after 5 s (v) = 0 + 10 × 5
   = 50 m/s
   Therefore, K.E = \(\frac { 1 }{ 2 }\) × 2 × (50)²
   = 2500 Joule = 2.5 KJ

Answer 13.

1. The moving tanker completely filled with water is in the inertia of motion, both water and tanker experiences momentum. On applying sudden brakes the tanker will come to rest but the water will continue to remain in the state of motion and hence the tanker will lose the balance and topple.
2. The water will fall forward.
3. Abhishek shows the value of being intelligent, having scientific knowledge, helpful and caring.

Answer 14.
(a) 1 kW h = 3.6 × 10⁶ Joules

Answer 15.

Answer 16.
Description:
Take an electric bell and an airtight glass jar. The electric bell is suspended inside the airtight glass jar, which is connected to a vacuum pump.

Working:

1. When we press the switch, we’ll be able to hear the bell.
2. When the air in the jar is pumped out gradually, the sound becomes feeble although the same amount of current is flowing through the bell.
3. When the air is removed completely, we’ll not be able to hear the sound of the bell.

Conclusion:
This experiment shows that sound requires a medium for its propagation.

Answer 17.
AIDS is considered as a syndrome because the AIDS virus damages the immune system of the body and the body can no longer fight against even the minor infections. Any small health problem can become a major infection and damage the entire organ or a system. The effect of disease becomes very severe and complex, at times killing the person from AIDS. Hence there is no specific disease symptoms for AIDS, but it results in a complex diseases and ultimately leads to death.

Answer 18.

Answer 19.
(a) When a body moves in a circular path with uniform speed, its motion is called uniform circular motion.
(b) Radius = 50 m
Time = 50 s

1. The distance covered by an athlete A to B i.e., semicircle of the track
∴ Circumference = 2 πr
∴ Half-circumference = πr
= \(\frac { 22 }{ 7 }\) × 50
∴ Distance = 157.14 m

2. Displacement from A to B is diameter AB
d= 2r
∴ d= 2 × 50= 100 m

3. Speed = ?
Speed = \(\frac { Distance }{ time }\) = \(\frac { 157.14 }{ 50 }\) = 3.143
∴ Speed = 3.143 m/s

Answer 20.
(a) Rutherford’s scattering experiment
He selected very thin gold foil to be bombarded with fast moving a-particles – which were positively charged ‘He’ ions.
The fast moving a-particles have a considerable amount of K.E. to hit the gold atoms
Observations

• Most of the a-particles passed straight through the foil without any deflection.
• One out of 20,000 particles appeared to rebound.

Inference

• There is a positively centre inside the atom called nucleus.
• The electrons revolve around the nucleus in well defined orbits.
• The size of the nucleus is very small as compared to the size of the atom.

(b) Atomic number is 17
Element is chlorine
Electronic configuration – 2, 8, 7; valency – 1
OR

1. Separating funnel
2. Sublimation
3. Evaporation/crystallisation
4. Magnetic separator
5. Centrifugation

Answer 21.
‘Energy possessed by object by virtue of its position or configuration’ (to be explained in candidate’s own words).
Example: Stretched string of bow/ a stone lifted to a certain height (or any other appropriate example).
S.I. unit-joule

Let an static object of mass, m be raised to a height h above the ground.
Then, Force required to raise the object = Weight of the object
= mg
Now, Work done on the object, W = Force × displacement
= mg × h
This work done is the stored potential energy of the object,
∴ P.E. = mgh
As the object falls down, m = 20 kg; g = 10 m/s²; h = 10 m
∴ P.E. = mgh = 20 kg × 10 m/s² × 10 m
P.E. = 2000 J
Its P.E. gets converted to K.E.
Kinetic energy just before it touches = 2000 J

SECTION-B

Answer 22.
In an open container, the gaseous product, carbon dioxide will escape into the atmosphere and the observed final mass will be less than the actual final mass.

Answer 23.
Presence of chitinous covering that prevents desiccation.

Answer 24.

1. The measuring cylinder should be kept on the plain flat surface.
2. The lower meniscus of water and the eye level should be parallel and in straight line.

Answer 25.
‘The compound, iron sulphide reacts with dilute sulphuric acid to form hydrogen sulphide gas. This gas is a colourless gas with the smell of rotten eggs.

Answer 26.
Mass of (copper sulphate + sodium sulphide) = Mass of (copper sulphide + sodium sulphate)
15.9g + 7.8 g = 9.5 g + x
x = 23.7g

Answer 27.
The stages during the life cycle of mosquito is:

• eggs
• larva
• pupa
• adult.

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CBSE Sample Papers for Class 9 Science Paper 3 are part of CBSE Sample Papers for Class 9 Science. Here we have given CBSE Sample Papers for Class 9 Science Paper 3.

CBSE Sample Papers for Class 9 Science Paper 3

Students who are going to appear for CBSE Class 9 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 3 of Solved CBSE Sample Paper for Class 9 Science is given below with free PDF download solutions.

Time Allowed : 3 Hours
Max. Marks: 80

General Instructions

• The question paper comprises of two Sections, A and B. You are to attempt both the sections.
• All questions are compulsory. However an internal choice will be provided in two questions of 3 marks each and one question of five marks.
• All questions of Section A and all questions of Section B are to be attempted separately.
• Question numbers 1 to 2 in Section A are one-mark questions. These are to be answered in one word or in one sentence.
• Question numbers 3 to 5 in Section A are two-marks questions. These are to be answered in about 30 words each.
• Question numbers 6 to 15 in Section A are three-marks questions. These are to be answered in about 50 words each.
• Question numbers 16 to 21 in Section A are five-marks questions. These are to be answered in about 70 words each.
• Question numbers 22 to 27 in Section B are two-marks questions based on practical skills. These are to be answered in brief

Questions
SECTION-A

Question 1.
What is the charge and mass of proton?

Question 2.
What is haemocoel? Which group of animals have haemocoel?

Question 3.
The number of electrons in the outermost shell of chlorine is 7. What is its valency and why?

Question 4.
How will you differentiate between a primitive organism from the advanced organisms?

Question 5.
Explain why feather falls slowly than a coin under gravity through air.

Question 6.
State one feature that is similar and one feature that is dissimilar with respect to mitochondria and plastids.

Question 7.
What is meant by the term mole? Calculate the number of moles in
(a) 3.011 × 10²³ atoms of C
(b) 32 g of oxygen gas
[N_A = 6.022 × 10²³ mol^-1, At. Mass of O = 16 u and C = 12 u]

Question 8.
State the distinguishing characteristics of the division Thallophyta.
OR
State three ways in which phloem is different from Xylem.

Question 9.
List the names of three diseases caused by virus stating their mode of communication in each mode.
OR

1. Why is making of anti-viral medicines harder than anti-bacterial medicines?
2. How can we prevent the exposure to infectious microbes?

Question 10.
Define pressure and its S.I. Unit. The dimensions of a metallic cuboid are 30 cm × 20 cm × 15 cm and its mass is 30 kg. If the acceleration due to gravity be 10 m/sec², Calculate the pressure exerted by the cuboid, when it is resting on the face having sides 20cm × 15 cm on a table.

Question 11.
State the law of conservation of momentum. Why a person is hit harder when he falls on a hard floor than when he falls on a heap of sand from the same height?
A bullet of mass 20 g is fired horizontally with a velocity 100 m/s from a pistol of mass 1.5 kg. Calculate the recoil velocity of the pistol.

Question 12.
Give an example in each case where work done by a force is:

1. Zero
2. Positive
3. Negative

Question 13.
A goldsmith measured the purity of gold by using a special measuring device. He told the customer that there was impurity present in gold ornament that he wanted to buy and it was not 22 carats but 18 carats jewellery.

1. How can we find the purity of gold?
2. What is the unit of relative density?
3. What value of goldsmith is reflected in this act?

Question 14.
Silver nitrate solution was mixed with 5 g of sodium chloride solution to verify the law of conservation of mass. 8.1 gram of silver chloride was formed and sodium nitrate formed was equal to half of the amount of silver nitrate solution used. What is the amount of AgNO₃ used and NaNO₃ formed.

Question 15.

1. Why are the roofs and walls of an auditorium hall generally covered with sound absorbent materials?
2. The sound of ringing bell inside a vacuum chamber can’t be heard. Why?

Question 16.
A silver ornament of mass ‘m’ grams is polished with gold equivalent to 1% of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.

Question 17.
Explain the structure of the human ear with the help of a diagram.

Question 18.
What do you mean by work? Give an example of negative work done? What is the work done to increase the velocity of a car from 18 km/hr to 90 km/hr, if the mass of the car is 2000 kg.

Question 19.

1. State two factors on which the magnitude of buoyant force acting on a body immersed in a fluid depends.
2. Will the buoyant force exerted by a liquid increase, if its volume is increased?
3. Name some devices based on the Archimedes principle.

Question 20.
Continuous addition of fertilisers to the soil destroys its fertility. Long term fertilisers use is substituted with the various cropping pattern to maintain the fertility of the soil. Discuss few cropping patterns, their techniques and benefits.
OR

1. Define vaccine. Name two vaccines given to children.
2. What is antibiotic penicillin? Explain its functioning.

Question 21.

1. List four main processes involved in the water cycle.
2. Give a diagrammatic representation of Nitrogen cycle in nature.

SECTION-B

Question 22.
The length, breadth and height of a cuboid of mass m kg are 5 cm, 3 cm and 2 cm respectively. Calculate the surface area of the surface where the pressure on the floor will be maximum.

Question 23.
Write the difference between male and female cone of Pinus?

Question 24.
In a chemical reaction, sodium carbonate (5.3 g) reacts with and ethanoic acid (6 g) forms (8.2 g) sodium ethanoate, (2.2 g) carbon dioxide and (0.9 g) water.
Does the product formed follow the law of conservation of mass.

Question 25.
In a plant, name two features which you would examine to categorise it into a monocot or a dicot plant.

Question 26.
How does a cockroach adapt itself to a wide range of habitats?

Question 27.
What are the different adulterants commonly found in foods?

Answers
SECTION-A

Answer 1.
Proton has positive charge. Its mass is 1.675 × 10^-27 kg.

Answer 2.
Haemocoel is a pseudocoel with blood. It is found in arthropods and molluscs.

Answer 3.
Its valency is one because it can gain one electron to become stable like its nearest noble gases argon.

Answer 4.
The group of organisms which have ancient body designs and have not changed much are called “primitive” organisms. They are different from the advanced organisms as advanced organisms are group of organisms which have acquired their particular body designs recently.

Answer 5.
Air resistance depends on the surface area which is more in case of feather.

Answer 6.
Similar feature: Both have their own DNA and ribosome to synthesise their own proteins.
Dissimilar feature: Mitochondria is the site of cellular respiration and release energy, while plastids with chlorophyll are centre for photosynthesis and store energy.

Answer 7.
Mole is defined as the counting unit at atomic & molecular level and is equal to 6.022 × 10²³ atoms which is the number of atoms 12 g of ₁₂C isotope.

Answer 8.
The characteristic features of the division Thallophyta are:

• The plant body consists of individual thallus.
• The sex organs are single celled.
• After fertilisation, no embryo is formed.

OR

• Phloem allows the movement of materials in both the directions and Xylem allows the movement in only one direction(upwards).
• Phloem transports food from leaves to all parts of the plant body and Xylem transports water and minerals from roots to all the parts of the plant body.
• Phloem does not use suction pull force like xylem and it does not many dead cells as xylem has.

Answer 9.

• Jaundice – Contaminated food and water.
• Rabies – Saliva of infected animal.
• AIDS – Through sexual contact, blood transfusion, reusing the contaminated needle, from infected mother to the foetus.

OR
1. Antibiotics block the bacterial process that builds the cell wall in bacteria. As a result, the growing bacteria become unable to make cell wall and dies away easily. Viruses do not have any biochemical mechanism of their own. They enter our cells and use our machinery for their life processes. Therefore making of anti-viral medicine is difficult than anti-bacterial medicine.

2. We can prevent exposure to airborne microbes by providing living conditions that are not overcrowded. Exposure to waterborne microbes can be prevented by providing safe . drinking water. This can be done by proper scientific way of treating the water to kill any microbial contamination. Exposure to vector-borne microbes can be prevented by living in a clean environment.

Answer 10.
Pressure is defined as thrust per unit area (or force acting per unit area). Its SI unit is Pascal, (Pa)
m = 30 kg
A = 20 cm × 15 cm = 300 cm²
= 0.03 m²
g = 10 m/s²
p = \(\frac { mg }{ V }\) = \(\frac { 30\times 10 }{ 0.03 }\)
= 10⁴ Pa

Answer 11.
Law of conservation of momentum: The sum of the momenta of the two objects before collision is equal to the sun of the momenta after collision, provided there is no external unbalanced force acting on them.
When a person falls on the hard floor, he is brought to rest in a very short interval of time, so a greater force come into play.
On the other hand when he falls on a heap of sand, he is brought to rest in a longer time, so lesser force come into play/explanation in terms of momentum.

Total momentum before firing (pistol & bullet) = 0
Total momentum after firing (of pistol & bullet) is
= 0.02 kg × ( 100 m s^-1) + 1.5 kg × v ms^-1
= (2 + 1.5 v) kg ms^-1
Total momenta after firing = total momenta before firing
2 + 1.5 v = 0
1.5 v = -2
∴ v = 1.33 m/s

Answer 12.

1. work done by gravity on a rolling ball.
2. hitting a stationary ball.
3. work done by a friction of a rolling bail.

Answer 13.

1. The purity of gold can be found out by knowing the density of the gold.
2. Relative density does not have any unit.
3. Goldsmith showed the value of honesty and he is trustworthy.

Answer 14.
Let the mass of AgNO₃ used be x.
Then, mass of NaNO₃ formed will be \(\frac { x }{ 2 }\)
Mass of reactants = Mass of products
x + 5 = 8.1 + \(\frac { x }{ 2 }\)
\(\frac { x }{ 2 }\) = 3.1
x = 6.10 g
Mass of AgNO₃ Used = 6.10 g
Mass of NaNO₃ formed = \(\frac { 6.10 }{ 2 }\) = 3.05 g

Answer 15.

1. If absorbent materials are absent then there will be multiple echoes, due to which sound cannot be heard clearly.
2. Sound waves are mechanical waves and cannot travel through vaccum.

Answer 16.

Answer 17.

(a) Outer Ear: Pinna, auditory canal and tymphanic membrane.

• Pinna – It collects the sound from the surroundings.
• Auditory Canal – The sound waves collected pass through this canal.
• Tymphanic Membrane – It is a thin membrane which receives the vibrations of sound. A compression reaches the ear drum, the pressure on the outside of the membrane increases and pushes the ear drum inwards, and moves out when the rarefaction reaches the ear drum.

(b) Middle Ear: Consists of three small bones called hammer, anvil and stirrup. The vibrations are received by these three bones and the strength of vibrations is increased i.e., the sound is amplified and passed to inner ear.
(c) Inner Ear: It consist of cochlea and auditory nerve. Cochlea receives the amplified vibrations and convert them into electrical signals. These electrical signals are sent to the brain via the auditory nerve and brain interprets the signals as sound.

Answer 18.
Work is said to be done when the force applied on an object moves it in its own direction.
Example of negative work done – When a body is sliding on a surface, work done by force of friction is negative.

Answer 19.

1. Buoyant force = Weight of liquid displaced
   = (Volume of the liquid displaced) × (Density of liquid) × (Acceleration due to gravity)
   So, density of liquid and volume of the liquid displaced affects the buoyant force.
2. Buoyant force exerted by liquid does not depend upon its volume.
   So, the buoyant force will not increase on increasing the volume of the liquid.
3. Hydrometer and lactometer are based on Archimedes’ principle. Submarines are also designed according to Archimedes’ principle.

Answer 20.
Three different cropping patterns, namely mixed cropping, inter-cropping and crop-rotation are generally practised.
1. Mixed cropping allows two or more crops to be owed simultaneously on the same piece of land. Wheat and gram, wheat and mustard, groundnut and sunflower etc. are some common examples of crops grown through mixed cropping. Crops are chosen in such a way that they require different amounts of minerals.

2. Inter-cropping allows farmers to grow two or more crops simultaneously in the same field in a definite pattern. For example, cauliflower and chilli plants are grown together in alternating rows on a single field. To ensure that maximum utilisation of the nutrients applied, crops are selected in such a way that their nutrient requirements are different. Other examples of crops grown through inter-cropping include soyabean and maize, finger millet (bajra) and cow-pea (lobia) etc.

3. Crop-rotation is the practice of growing two or more varieties of crops in the same field in sequential seasons. A common example of crop-rotation is to cultivate maize followed . by soyabean. This system helps in protecting crops from pests and diseases. The crops selected, vary in nutrient requirements. This ensures complete and uniform utilisation of the nutrients applied.
OR

1. Vaccine is a chemical/drug given in advance to a body to give immunity against certain diseases.
   Two vaccines given to children are:
   • BCG – for tuberculosis prevention
   • Polio drops – for polio prevention
2. Antibiotic penicillin is a vaccine which blocks the bacterial processes that build the cell wall when the bacteria infects a living person. Due to this drug, the bacteria is unable to make a protective cell wall and it dies away easily. It is used to cure the diseases and infections caused by bacteria.

Answer 21.
1. Evaporation – Condensation – Transpiration – Precipitation
2.

SECTION-B

Answer 22.
Surface having dimensions 3 cm and 2 cm, respectively, having surface area = (3 × 2) cm² has more pressure,
∵ Pressure is inversely proportional to area. If area is less, pressure is more.

Answer 23.

• Female cones are large and woody.
• Male cones are smaller and tender.

Answer 24.
Sodium carbonate + Ethanoic acid → Sodium ethanoate + Carbon Dioxide + Water.

∵ It follows the law of conservation of mass.

Answer 25.
In any given plant to classify it as monocot or dicot, we need to see the venation in leaves, reticulated net like pattern refers to dicot plant and parallel venation refers to monocot plant.

Answer 26.
Cockraoch has a hard exoskeleton that serves many functions, including protection from water, loss and physical injury and internally required for muscle attachment, which results in tremendous leverage and strength. It also undergoes hibernation during unfavorable conditions.

Answer 27.
The commonly used adulterants in food are:

• Black pepper – dry seeds of papaya
• Honey – Jaggery
• Mustard seeds – argemone seeds
• Red chilli powder – red brick powder

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