CBSE Class 9

HOTS Questions for Class 9 Science Chapter 8 Motion

These Solutions are part of HOTS Questions for Class 9 Science. Here we have given HOTS Questions for Class 9 Science Chapter 8 Motion

Question 1.
Under what condition, the average speed is equal to the magnitude of the average velocity. Justify your answer.
(CBSE 2010, 2012)
Answer:

Now, the average speed = magnitude of average velocity if the total distance travelled by an object in a given time interval is equal to the magnitude of the displacement of the object in the same time interval. This is possible, when an object moves in one direction along a straight line. Thus, average speed is equal to the magnitude of the average velocity if an object moves in one direction along a straight line.

More Resources

• HOTS Questions for Class 9 Science
• NCERT Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• NCERT Exemplar Solutions for Class 9 Science
• Previous Year Question Papers for CBSE Class 9 Science

Question 2.
A body can have zero average velocity but not zero average speed. Explain. (CBSE 2013)

Or

Give an example of a motion in which average velocity is zero, but the average speed is not zero. (CBSE 2015)
Answer:

Since, the total distance travelled by a moving body increases with the time, so average speed of a moving body can not be zero.

Since total displacement of a moving body can be zero, so the average velocity of a moving body can be zero.
Example. When an athlete completes one round in a circular track in the given time interval, then his total displacement is zero but total distance travelled is equal to the length of the circular track. Hence, his average velocity is zero but his average speed is not zero.

Question 3.
An object P is moving with a constant velocity for 5 minutes. Another object Q is moving with changing velocity for 5 minutes. Out of these two objects, which one has acceleration. Explain. (CBSE 2012)
Change in velocity
Answer:

Since, the velocity of object P is not changing or change in velocity of the object is zero, therefore, object P has no acceleration. On the other hand, there is change in velocity of the object Q, so it has acceleration.

Question 4.
Can an object be accelerated if it is moving with constant speed ? Justify your answer with an example.

Or

Can a body have constant speed and still be accelerating ? Give an example. (CBSE 2010)

Or

Explain how is it possible for an object to move with a constant speed but with uniform acceleration.
(CBSE 2012)
Answer:
An object moving with constant speed can be accelerated if its direction of motion changes. For example, an object moving with a constant speed in a circular path has an acceleration because its direction of motion changes continuously.

Question 5.
Two trains A and B start moving at the same time. The distances travelled by them in given intervals of time are given below. State which train has uniform motion and which train has non-uniform motion.

Answer:
Since train A travels equal distances in equal intervals of time (i.e. in every 15 minutes), so the motion of train A is uniform motion. On the other hand, train B travels unequal distances in equal intervals of time (i.e. in every 15 minutes), so the motion of train B is non-uniform motion.

Hope given HOTS Questions for Class 9 Science Chapter 8 Motion are helpful to complete your science homework.

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NCERT Solutions for Class 9 Science Chapter 8 Motion

These Solutions are part of NCERT Solutions for Class 9 Science. Here we have given NCERT Solutions for Class 9 Science Chapter 8 Motion. LearnInsta.com provides you the Free PDF download of NCERT Solutions for Class 9 Science (Biology) Chapter 8 – Motion solved by Expert Teachers as per NCERT (CBSE) Book guidelines. All Chapter 8 – Motion Exercise Questions with Solutions to help you to revise complete Syllabus and Score More marks.

More Resources

• NCERT Solutions for Class 9 Science
• HOTS Questions for Class 9 Science
• Value Based Questions in Science for Class 9
• NCERT Exemplar Solutions for Class 9 Science
• Previous Year Question Papers for CBSE Class 9 Science

NCERT TEXT BOOK QUESTIONS

IN TEXT QUESTIONS

Question 1.
An object has moved through a distance. Can it have zero displacement ? If yes, support your answer with an example. (CBSE 2015)
Answer:
Yes, The displacement of the object can be zero. Let a boy completes one round of a circular track in 5 minutes. The distance travelled by the boy = circumference of the circular track. However, displacement of the boy is zero because his initial and final positions are same.

Question 2.
A farmer moves along the boundary of a square field of side 10 m in 40 s.
What will be the magnitude of displacement of the farmer at the end of 2 minutes 20 seconds ? (CBSE 2010, 2015)

Answer:
ABCD is a square field of side 10 m.
The farmer moves along the boundary of the field from the corner A via the corners B, C and D.
After every 40 s, the farmer is again at the corner A, so his displacement after every 40 s is zero.
At the end of 2 minutes 20 seconds = (2 x 60 + 20) = 140 s, the farmer will be at the corner C.

Question 3.
Distinguish between speed and velocity. (CBSE 2010, 2012, 2013, 2015)
Answer:

Question 4.
Under what conditions) is the magnitude of the average velocity of an object equal to its average speed ? (CBSE 2012, 2013)
Answer:
When an object moves in one direction along a straight line.

Question 5.
What does the odometer of an automobile measure ? (CBSE 2010, 2011, 2014, 2015)
Answer:
Odometer of an automobile measures distance travelled by the automobile.

Question 6.
What does the path of an object look like when it is in uniform motion ? (CBSE 2012)
Answer:
Straight path.

Question 7.
During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station ? The signal travels at the speed of light, that is, 3 x 10⁸ m s^-1
Answer:

Question 8.
When will you say a body is in

1. uniform acceleration ?
2. non-uniform acceleration (CBSE 2012, 2013)

Answer:

1. A body has uniform acceleration if its velocity changes by an equal amount in equal intervals of time. .
2. A body has non-uniform acceleration if its velocity changes by unequal amount in equal intervals of time.

Question 9.
A bus decreases its speed from 80 kmh^-1 to 60 kmh^-1 in 5 s. Find the acceleration of the bus.
(CBSE 2010, 2011, 2012, 2015)
Answer:
Here,

Question 10.
A train starting from a railway station and moving with a uniform acceleration attains a speed of 40 km h^-1 n 10 minutes. Find its acceleration.
Answer:

Question 11.
What is the nature of the distance-time graphs for uniform and non-uniform motion of an object ?
(CBSE 2012)
Answer:

1. For uniform motion, distance-time graph is a straight line having constant gradient or slope as shown in figure.
2. For non-uniform motion, distance-time graph is a curve having increasing gradient or slope or decreasing gradient as shown in figures.
   

Question 12.
What can you say about the motion of an object whose distance-time graph is a straight line parallel to
the time axis ? (CBSE 2010, 2012)
Answer:
When distance-time graph is a straight line parallel to the time axis, it means, the distance of the object is not changing with time. Thus, the object is stationary.

Question 13.
What can you say about the motion of an object if its speed-time graph is a straight line parallel to the time-axis ?
Answer:
In this case, speed of the object is constant. That is, the object travels equal distances in equal intervals of time along a straight line. Hence, motion of the object is uniform motion.

Question 14.
What is the quantity which is measured by the area occupied below the velocity-time graph ?
(CBSE 2010, 2012)
Answer:
Magnitude of the displacement of a body is measured by the area under the velocify-time graph.

Question 15.
A bus starting from rest moves with a uniform acceleration of 0.1 m s^-2 for 2 minutes. Find
(a) the speed acquired,
(b) the distance travelled. (CBSE 2012)
Answer:

Question 16.
A train is travelling at a speed of 90 km h^-1. Brakes are applied so as to produce a uniform acceleration of – 0.5 m s^-2 . Find how far the train will go before it is brought to rest ?
Answer:

Question 17.
A trolley, while going down an inclined plane has an acceleration of 2 cm s^-2. What will be its velocity 3 s after the start ?
Answer:
Here, u = 0,v = ?, a = 2 cm s^-2, t = 3 s
Using, v = u + at, we get
v = 0 + 2 x 3 = 6 cm s^-2.

Question 18.
A racing car has a uniform acceleration of 4 m s^-2. What distance will it cover in 10 s after start ?
Answer:

Question 19.
A stone is thrown in a vertically upward direction with a velocity of 5 m s^-1 If the acceleration of the stone during its motion is 10 m s^-2 in the downward direction, what will be the height attained by the stone and how much time will it take to reach there ?
Answer:

NCERT CHAPTER END EXERCISE

Question 1.
An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes and 20 s ?
Answer:

(ii) After every 40 s, athlete reaches his starting point, so after 40 s, his displacement is zero. It means, the athlete completes the circular track 3 times in 120 s and in the next 20 s, he is just opposite to his starting point. Therefore, the magnitude of the displacement of the athlete at the end of the 140 s (or 2 minutes 20 s) = Diameter of the circular track = 200 m.

Question 2.
Joseph jogs from one end A to the other end B of a straight 300 m road in 2 minutes 50 seconds and then turns around and jogs 100 m back to point C in another 1 minute. What are Joseph’s average speeds and velocities in jogging
(a) from A to B and
(b) from A to C ? (CBSE 2010, Term I)
Answer:
Distance from A to B – 300 m
Displacement from A to B = 300 m
Time taken to go from A to B =2 minutes 50 s = 170 s

Question 3.
Abdul, while driving to school, computes the average speed for his trip to be 20 km h^-1. On his return trip along the same route, there is less traffic and the average speed is 40 km h^-1. What is the average speed for Abdul’s trip ? (CBSE 2011)
Answer:

Question 4.
A motor boat starting from rest on a lake accelerates in a straight line at a constant rate of 3.0 m s^-2 for 8.0 s. How far does the boat travel during this time ? (CBSE 2011, 2013)
Answer:

Question 5.
A driver of a car travelling at 52 km h^-1 applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 km h^-1 in another car applies his breaks slowly and stops in 10 s. On the same graph paper plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied ?
Answer:

Question 6.
Figure shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions :

(a) Which of the three is travelling the fastest ?
(b) Are all three ever at the same point on the road ?
(c) How far has C travelled when B passes A ?
(d) How far has B travelled by the time it passes C ?
Answer:
(a) Speed = Slope of distance-time graph.
Since slope of distance-time graph for object B is the greatest, so object B is travelling the fastest.
(b) All the three objects will be at the same point on the road if all the three distance-time graphs intersect each other at a time. Since, all the three distance-time graphs do not intersect each other at a time, so they are never at the same point on the road.
(c) When B passes A, distance travelled by C = 9.6 – 2 = 7.6 km.
(d) Distance travelled by B by the time it passes C = 6 km.

Question 7.
A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 m s^-2, with what velocity will it strike the ground ? After what time will it strike the ground ?
Answer:

Question 8.
The speed time graph for a car as shown in figure

(a) Find how far does the car travel in the firdt four seconds.
Shade the area on the graph that represents the distance travelled by the car during the period.
(b) Which part of the graph represents uniform motion of the car?
Answer:
(a)


(b) The straight part of the curve parallel to time axis represents the uniform motion of the car.

Question 9.
State which of the following situations are possible and give an example for each of these :
(a) an object with a constant acceleration but zero velocity.
(b) an object moving with an acceleration but with uniform speed.
(c) an object moving in a certain direction with an acceleration in the perpendicular direction.
(CBSE 2012)
Answer:
(a) When an object is thrown vertically upward, its velocity at the highest point is zero but it has constant acceleration = 9.8 m s^-2
(b) Uniform circular motion.
(c) An object moving in a circular path with uniform speed, its acceleration is always perpendicular to the direction of the motion of the object.

Question 10.
An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate its speed if it takes 24 . hours to revolve around the earth. (CBSE 2011)
Answer:

NCERT Solutions for Class 9 Science Chapter 8 Motion

Hope given NCERT Solutions for Class 9 Science Chapter 8 are helpful to complete your science homework.

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NCERT Exemplar Solutions for Class 9 Science Chapter 14 Natural Resources

These Solutions are part of NCERT Exemplar Solutions for Class 9 Science . Here we have given NCERT Exemplar Solutions for Class 9 Science Chapter 14 Natural Resources

Question 1.
Rivers from land, add minerals to sea water. Discuss how.
Answer:
Rivers are formed from springs, melting snow and rain water flowing over land as run off. While, passing through and over the rocks, the flowing water picks up minerals. These dissolved minerals are taken by rivers to sea and make them available to marine organisms.

More Resources

• NCERT Exemplar Solutions for Class 9 Science
• NCERT Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science
• Previous Year Question Papers for CBSE Class 9 Science

Question 2.
How can we prevent loss of top soil ?
Answer:
Control of Soil Erosion: Soil erosion can be prevented by providing plant cover to soil. Roots of plants hold the soil firmly around them. They increase water percolation during rains and decrease runoff. Vegetation cover also reduces direct pounding of soil by rain drops. The various methods to control soil erosion are as follows :

1. Vegetation Cover: Soil should not be left uncovered. Tree plantation should be undertaken where vegetation cover is poor or absent.
2. Controlled Grazing: Grazing should be limited to certain seasons and for limited number of animals.
3. Slope is divided into a number of flat fields for slowing down the flow of water.
4. Contour Bunding: Small bunds are raised on the edges of fields to prevent loss of top soil through wind or water.
5. Conservation Tillage: Instead of conventional tillage, reduced or no tillage can be practised. It prevents erosion.
6. Wind Breaks: Wind erosion is reduced if rows of trees and shrubs are planted at right angles to the prevailing direction of wind.

Question 3.
How is the life of organisms living in water affected when water gets polluted ? (CCE 2012)
Answer:
Water gets polluted from domestic wastes, fertilizers, pesticides (from fields) and industrial wastes.

1. Fertilizers and domestic wastes cause eutrophication or excessive growth and increased organic loading. This, reduces oxygen available to aquatic animals,
2. Domestic waste carries pathogens of a number of diseases. Some of them can cause diseases in aquatic animals as well,
3. Pesticides and industrial wastes carry toxins that directly harm the aquatic organisms.

Question 4.
During summer, if you go near the lake, you feel relief from heat. Why ?
Answer:
During day time, air over the land becomes heated up, rises upward and creates an area of low pressure. Lake water is not heated up so quickly. Evaporation of water from its surface also cools it up. Therefore, air over the surface of lake is cooler. It moves towards the land where low pressure exists. Therefore, during day dme a cool breeze flows from lake to the land nearby.

Question 5.
In coastal area, wind current moves from sea towards the land during day but during night it moves from land to the sea. Discuss the reason.
Answer:
Air Movement in Coastal Areas: In coastal areas, there is a regular flow of cooler air from sea towards the land during the daytime. It is because during the daytime land gets heated faster than water. Reradiation from land heats the air above it. The hot air rises and creates an area of low pressure. Sea water is not heated so rapidly. Air above sea remains comparatively cool. It has a higher pressure as compared to air over land. Therefore, cooler air present over sea moves towards land where low pressure exists.

Question 6.
Following are a few organisms :
(a) Lichens
(b) Mosses
(c) Mango tree
(d) Cactus.
Which among the above can grow on stones and also help in formation of soil ? Write the mode of their action for making soil.
Answer:
Lichens and Mosses.
Weathering by Living Organisms:
Living Organisms are cause biological weathering. Lichens growing on rock surface are able to extract minerals from the same. This produces small crevices where a thin layer of soil builds up. Mosses grow over these crevices. They cause deepening of crevices and building up of more soil in them. Deeper crevices form cracks.
The cracks become bigger when the roots of short lived herbs pass into them. With the passage of time roots of bigger plants pass into cracks. Cracks widen and cause slow fragmentation and later pulverisation of rocks.

Question 7.
Soil formation is done by both abiotic and biotic factors. List the name of these factors by classifying them as abiotic and biotic.
(CCE 2012)
Answer:
Abiotic Factors : Sun, water, wind.
Biotic Factors : Lichens, mosses, herbs, shrubs and trees.

Question 8.
All the living organisms are basically made up of C, N, S, P, H and O. How do they enter the living forms ? Discuss.
Answer:
Most of them first enter plants and become components of organic materials during the process of photosynthesis. They enter plants from air (CO₂), water and ions (from soil). From plants the chemicals pass on to other organisms.

Question 9.
Why does the percentage of gases like oxygen, nitrogen and carbon dioxide remain almost the same in the atmosphere ?
Answer:
Through biogeochemical cycling where there is repeated circulation of biogenetic nutrients between abiotic and biotic components of the environment.

Question 10.
Why has moon very cold and very high temperature variations, e.g., from -190°C to 110°C even though it is at the same distance from the sun as the earth is ? (CCE 2012)
Answer:
Moon does not possess atomosphere. Atmosphere being a bad conductor acts as a temperature buffer on earth. This is not so on the moon. Therefore, moon gets heated up as the sun rays fall on its surface. It cools down drastically when there is no sunlight.

Question 11.
Why do people love to fly kites near the sea shore ? (CCE2012)
Answer:

1. There is a regular unidirectional wind from sea to land.
2. It helps in flying the kite high.
3. The wind is cooler and provides comfort even in bright sun.

Question 12.
Wliy does Mathura refinery pose problems to the Taj Mahal ? (CCE 2014)
Answer:
Mathura refinery emits hydrocarbons and sulphur oxides. Hydrocarbons induce the formation of ozone which is highly oxidising. Sulphur dioxide produces acid rain which has a corroding effect on marble. Therefore, Mathura refinery does pose problems to Taj Mahal.

Question 13.
Why do not lichens occur in Delhi/Mumbai whereas they commonly grow in Manali/Ooty or Darjeeling ? (CCE 2011, 2012)
Answer:
Lichens are sensitive to sulphur dioxide which occurs in sufficient quantity in the atmosphere of Delhi due to large number of
vehicles, homes and factories using fossil fuels. Moreover, Delhi occurs in semi-arid area where, atmospheric moisture is low. In Manali and Darjeeling, the atmosphere is humid and sulphur dioxide pollution is comparatively low.

Question 14.
Wliy does water need conservation even though large oceans surround the land masses ? (CCE 2012)
Answer:
Marine water is unfit for consumption by humans, industries or land plants and animals. Therefore, terrestrial biota and human beings have to depend upon fresh water resources available on land (only about 0.5% of the total). The same has to be conserved.

Question 15.
There is a mass mortality of fish in a pond. What may be the reasons ?
Answer:

1. Passage of pesticide rich water from crop fields. ,
2. Pouring of industrial waste. .
3. Pouring of hot water from an industry or thermal power plant.
4. Release of waste rich in heavy metal and mercury.
5. Blockage of fish gills by some suspended pollutant.
6. Excessive eutrophication.

Question 16.
Lichens are called pioneer colonisers of bare rock. How can they help in formation of soil ?
Answer:
Ans. Lichens release small quantity of acids which corrode the surface of rocks creating small pores and releasing minerals. With the passage of time the porous surface changes into thin layer of soil.

Question 17.
“Soil is formed by water”. If you agree with this statement, then give reasons.
Answer:
Yes,  “action of water in weathering” (wetting and drying, frost action, abrasion).

1. Wetting and Drying. Certain rock components can pick up and lose moisture. They undergo swelling and contraction resulting in fragmentation of rocks.
2. Frost Action. Water seeping in cracks would swell up and exert a great pressure if it freezes due to low temperature. The rock would undergo fragmentation.
3. Running water carrying rock fragments would break and grind rocks occurring in the pathway. Rain and hail also cause rock breaking.

Question 18.
Fertile soil has lots of hurpus. Why ? (CCE 2012)
Answer:
Fertile soils possess lots of humus because

1. Humus is required for binding soil particles into crumbs. Crumb formation is needed for both hydration and aeration of soil,
2. Humus makes the soil porous for easy passage of roots,
3. It is source of minerals.
4. Humus contains chemicals that promote growth of plants.

Question 19.
Why step farming is common in hills ?
Answer:
Step farming or terracing is carried out in the hills because it slows down the speed of rain water currents, checks soil erosion and increases water absorption by soil.

Question 20.
Why are root nodules useful for the plants ? (CCE 2012)
Answer:
Root nodules mostly occur in legume plants. These nodules contain nitrogen fixing bacteria named Rhizabium. The bacteria pick up nitrogen from soil atmosphere and convert it into organic compounds. The same pass into plant so that legumes become rich in proteins and other nitrogen compounds.

Question 21.
How do fossil fuels cause air pollution ? (CCE 2012)
Answer:
Fossil fuels (coal, petroleum) are burnt to obtain energy.
Combustion produces

1. Suspended particles
2. Sulphur oxides
3. Nitrogen oxides
4. Carbon monoxide
5. Vapours of hydrocarbons.

All these are air pollutants. Hydrocarbons are a source of cancer. They also damage internal organs. Alongwith nitrogen oxides, they produce ozone and smog. Sulphur and nitrogen oxides give rise to acid rain. They are also irritants and damage eyes and nasal tract.

Question 22.
What are the causes of water pollution ? Discuss how you can contribute in reducing water pollution ?
Answer:
Causes of Water Pollution:

1. 21% of all infectious diseases and 66% of all deaths of children below 5 years are caused by contamination of drinking and bathing water by pathogens present in sewage, e.g., cholera, typhoid, diarrhoea, dysentery, jaundice, etc.
2. Toxic Chemicals: Industrial effluents pass down a number of toxic chemicals, g., mercury by paper industry (minamata disease), cadmium (itai-itai disease), lead (plumbism), nitrate (met-haemoglobinaemia).

Reduction in Water Pollution :

1. Sewage: The authorities can be prevailed upon not to pass untreated sewage into water bodies.
2. Garbage: Domestic waste or garbage should not be thrown on the banks of water body.
3. Industrial Effluents. Asking the industrial houses not to pass the untreated effluents into water body.
4. Washing Clothes: Washing clothes should be discouraged on the banks of water bodies as detergents are a source of eutrophication.
5. Vegetation: Plant trees, shrubs and herbs on the banks. This checks soil erosion and siltation of water bodies. It also reduces run off from fields.

Question 23.
A motor car, with its glass totally closed, is parked directly under the sun. The inside temperature of the car rises very high. Explain why? (CCE 2012)
Answer:
Glass is transparent to sunlight, allowing it to pass into the interior of the car. It heats up the interior. But heat waves do not escape from the car due to glass being opaque to the same. As a result, the interior of the car placed in the sun will become very hot. It is similar to glass house effect.

Question 24.
Justify “Dust is a pollutant.” (CCE 2012)
Answer:

1. Dust consists of suspended particles. The latter pass into nasal tract and cause a lot of discomfort including allergic asthma, bronchitis, cough and cold,
2. Dust reduces light intensity,
3. Its particles are eye irritants,
4. Dust settles over plant foliage and reduces photosynthetic activity,
5. Dust particles block stomata reducing gaseous exchange,
6. Dust particles can pick up toxic metals and chemicals being emitted by industries.

Question 25.
Explain the role of the sun in the formation of soil.
Answer:

Paedogenesis: It is the process of formation of soil from rocky crust of earth. Paedogenesis occurs in two stages, weathering and humification.

1. Weathering
   It is the process of breaking down of rock present on the surface of earth into fine particles. Weathering is caused by three types of processes — physical, chemical and biological. Physical weathering is pulverisation of rocky matter caused by physical phenomena like atmospheric changes (heating, cooling, wetting-drying, frost action) and mechanical forces (abrasion by rain and hail, rolling stones carried by water, wave action, sand blast by wind). Chemical weathering is pulverisation of rocks by chemical action in wet weather like hydration, oxidation, reduction, carbonation and solubilisation. Biological weathering is the breaking down of rocks by the action of living organisms.
   Sun: It heats up the rocks during the day. Heating causes the rocks to expand. During night, the rocks cool and contract. Different parts of a rock expand and contract at different rates resulting in its cracking and breaking up into smaller pieces or fragments.
2. Humification
   It is the addition of partially decomposed organic matter or humus to the weathered rock particles to form soil. Humus binds the finely ground rock particles into aggregates called crumbs. Crumb formation is needed for both hydration and aeration of soil.

Question 26.
Carbon dioxide is necessary for plants. Why do we consider it as a pollutant ? (CCE 2014)
Answer:
Besides being essential for photosynthesis, carbon dioxide is a green house gas. Upto 350 ppm, it is both a good raw material as well as essential for keeping the earth warm. However, when its concentration rises (as presently it is 400 ppm), it becomes pollutant because it results in global warming. The latter is quite dangerous because it will melt polar ice, raise the water level of oceans and submerge several coastal areas and islands.

Hope given NCERT Exemplar Solutions for Class 9 Science Chapter 14 Natural Resources are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.

Value Based Questions in Science for Class 9 Chapter 14 Natural Resources

These Solutions are part of Value Based Questions in Science for Class 9. Here we have given Value Based Questions in Science for Class 9 Chapter 14 Natural Resources

Question 1.
It has been made mandatory to install rain water harvesting system and solar water heater in all buildings in urban areas,

1. What is the rationale when rain water already passes into drains ?
2. Why are solar water heaters being installed when electric geijers are available ?

Answer:

1. Rain water passed into drain does not enter the ground but is taken out of the urban area and poured into a water body at quite a distance with or without treatment. However, ground water is being withdrawn everywhere for drinking, industrial and irrigation purposes. As a result, the level of ground water is going down and arid conditions are being faced in many areas. In rain water harvesting, rain water from a building is passed directly into ground, dug wells or water pumps. This recharges ground water.
2. Installation of solar water heaters is a method of saving electricity which is always in short supply due to rapid urbanisation, Industrialisation and intensive agriculture. Coal/gas based power plants are adding CO₂ to the atmosphere causing global warming. Saving electricity is now an important social responsibility.

More Resources

• Value Based Questions in Science for Class 9
• HOTS Questions for Class 9 Science
• NCERT Solutions for Class 9 Science
• NCERT Exemplar Solutions for Class 9 Science
• Previous Year Question Papers for CBSE Class 9 Science

Question 2.

1. Sheela saw blue-green algae forming bloom in the village pond,
2. Fish, which was previously abundant was no-where to be seen.
3. The pond is giving a stink. Water of the pond is not even fit for cattle. Some of the cattle who were taken to the pond for drinking and bathing have fallen sick,
4. What explanation will Sheela give for this to the villagers.

Answer:

1. Bloom forming algae occur in a pond only when the quality of pond water has deteriorated due to pollution. Blue-green algae secrete toxins that are harmful to animals and humans,
2. Fish must have died due to deficiency of oxygen in pond water. Oxygen deficiency occurs when there is excess of organic matter (organic loading). The aerobic decomposers consume the dissolved oxygen. This is followed by anaerobic decomposition of organic matter. It produces sulphides and other sludge producing substances. Blue-green algae can grow under such circumstances.
3. Stink comes from anaerobic breakdown products of organic matter. The toxins released by blue-green algae further deteriorate the quality of water causing sickness and skin rashes in animals and humans.
4. Sheela could explain to the villagers that deterioration of pond has been due to excess fertilizers used by them in their fields. Rain wash brought these fertilizers into the pond. There was initial spurt in the growth of plants due to this. The phenomenon is called eutrophication. Excess plant matter slowly caused organic loading of water that reduced its oxygen content, killing the fish and other aquatic animals. So fertilizers should be used very judiciously in the fields.

Question 3.

1. Carbon dioxide concentration in the atmosphere has reached more than 390 ppm
2. The antarctic and arctic waters are becoming acidic causing thinning of animal shells.
3. Polar ice is melting,
4. Some low lying islands have submerged in sea.

(a) What are the reasons behind all these changes occurring on earth ?
(b) Suggest a mechanism to control the same and if possible to reverse the trend.

Answer:

(a) The reason for these global changes is faulty recycling of carbon dioxide. More of carbon dioxide is being produced than its consumption in photosynthesis due to

1. Excess combustion of fossil fuels in industries, power houses, automobiles, homes and other places,
2. Reduced intake of CO₂ by plants due to deforestation,
3. Higher amounts of CO₂ entering the atmosphere not only increases its atmospheric concentration but also the concentration of dissolved CO₂ in water, especially in colder seas. This is making colder waters acidic. The acidity is thinning the shells of many marine animals.
4. CO₂ is a green house gas which is causting global warming. Rise in global temperature is melting snow over poles. This is raising the level of sea water slowly. It was already submerged some low lying islands.

(b) Suggestions :

1. Large scale tree plantation in all vacant areas,
2. Reduced felling of forest trees.
3. Reducing consumption of fossil fuel by reducing dependence on thermal power plants, increasing efficiency of automobiles and switching over to alternate technologies that do not consume fossil fuels.

Question 4.
On a school trip to an industrial estate, students found that the marble used in the office buildings of most factories has lost its shine and become pitted.

1. What is the reason of marble pitting
2. Can this factor cause harm to vegetation as well ?
3. Suggest way to prevent this.

Answer:

1. Pitting and discolouring of marble is due to corrosive action of dry or wet acid rain, comprising sulphur dioxide and nitrogen oxides, emitted during combustion of fossil fuels in industries. The acid reacts with insoluble calcium carbonate of marble and converts it into soluble calcium sulphate and calcium nitrate.
2. Yes, Acid rain can also cause harm to vegetation by
   1. Direct action of acid over plants causing death of leaves,
   2. Solubilisation of essential minerals and their leaching leaving only toxic minerals in the soil.
3. Use of wet scrubbers to remove acidic gases from the industrial emissions.

Hope given Value Based Questions in Science for Class 9 Chapter 14 Natural Resources are helpful to complete your science homework.

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HOTS Questions for Class 9 Science Chapter 14 Natural Resources

These Solutions are part of HOTS Questions for Class 9 Science. Here we have given HOTS Questions for Class 9 Science Chapter 14 Natural Resources

Question 1.
(a) Fill in the blanks : A, B and C.

(b) Identify the biogeochemical cycle.
Answer:
(a) Fill in the blanks :
A- Organic molecules (C₆H₁₂O₆).
B- Photosynthesis.
C- Respiration.
(b) Identification: Oxygen cycle.

More Resources

• HOTS Questions for Class 9 Science
• NCERT Solutions for Class 9 Science
• Value Based Questions in Science for Class 9
• NCERT Exemplar Solutions for Class 9 Science
• Previous Year Question Papers for CBSE Class 9 Science

Question 2.
(a) Fill in the blanks: A to F.

(b) What will happen if the step A does not take place ?
(c) What will happen if the step F does not take place ?
Answer:
(a) Fill in the blanks :
A- Ammonification.
B- Ammonia.
C- Nitrites.
D- Nitrates.
E- Nitrification.
F- Denitrification.
(b) Absence of step A: No breakdown of proteins to release ammonia.
(c) Absence of step F: There will be no replenishment of atmospheric nitrogen.

Hope given HOTS Questions for Class 9 Science Chapter 14 Natural Resources are helpful to complete your science homework.

If you have any doubts, please comment below. Learn Insta try to provide online science tutoring for you.