CBSE Class X

Question 3:

Find out the source of water in your region/locality. Is water from this source

available to all people living in that area?

Answer:

The source of water in our region is ground water. Water from the source is

available to all the people living in that area.

Question 2:

Compare the above system with the probable systems in hilly/mountainous

areas or plains or plateau regions.

Answer:

In plains, the water harvesting structures are crescent-shaped earthen

embankments. These are low, straight, and concrete.

In hilly regions, the system of canal irrigation called Kulhs is used for water

harvesting.

This involves a collection of rain water in a stream, which is then diverted into

manmade channels down the hill sides.

Question 1:

Find out about the traditional systems of water harvesting/management in your

region.

Answer:

One of the traditional systems of water harvesting used in our region is tanks.

Question 2:

Suggest some approaches towards the conservation of forests.

Answer:

Some approaches towards the conservation of forests are as follows:

(a) People should show their participation in saving the forest by protesting

against the cutting of trees. For example, Chipko Andolan

(b) Planting of trees should be increased. Rate of afforestation must be more

than that of deforestation.

(c) Some people cut precious trees such as Chandan to earn money. Government

should take legal steps to catch these wood smugglers.

(d) Habitants of forests must not be bothered by the forest officials. Otherwise,

this would result in the clash between tribal people and the government officials,

thereby enhancing the naxal activities in forests.

Question 1:

Why should we conserve forests and wildlife?

Answer:

We should conserve forests and wildlife to preserve the biodiversity (range of

different life-forms) so as to avoid the loss of ecological stability. A large

number of tribes are the habitants in and around the forests. If the forests

are not conserved, then it may affect these habitants. Without proper

management of forest and wildlife, the quality of soil, the water sources,

and even the amount of rainfall may be affected. Without forest and

wildlife, life would become impossible for human beings.

Question 4:

Why do you think there should be equitable distribution of resources? What

forces would be working against an equitable distribution of our resources?

Answer:

Natural resources of the Earth must be distributed among the people uniformly

so that each and every one gets his share of the resource.

Human greed, corruption, and the lobby of the rich and powerful are the forces

working against an equitable distribution of resources.

Question 3:

How would these advantages differ from the advantages of using a long-term

perspective in managing our resources?

Answer:

In the case of a long-time perspective in managing our resources, these

resources will last for the generations to come. This management ensures

uniform distribution among the people. It conserves the natural resources

for many years and not just for a few years, as in the case of a short-term

perspective in conserving natural resources.

Question 2:

What would be the advantages of exploiting resources with short-term aims?

Answer:

There should be a judicious use of natural resources as they are limited in

nature. We should not exploit resources for our short term gains as this

would only lead to depletion of natural resources for the present generation

as well as generations to come. Hence,we can say that there are hardly any

advantages of exploiting natural resources for short term gains.

Question 1:

What changes can you make in your habits to become more environment-friendly?

Answer:

We should switch off the electrical appliances when not in use. Water and food

should not be wasted. Close the tap when not in use. Dump the objects made

of plastic and glass in designated recycling boxes. Plastic, paper, or glass must

be recycled or reused and not dumped with other wastes. This is because

objects made of plastic do not get decomposed easily. Besides soil fertility,

they badly affect our environment. We should dispose the wastes safely and

not disperse in public places. These are a few things that can be done to

become more environment- friendly.

Question 10:

What are the environmental consequences of the increasing demand for energy?

What steps would you suggest to reduce energy consumption?

Answer:

Industrialization increases the demand for energy. Fossil fuels are easily

accessible sources of energy that fulfil this demand. The increased use

of fossil fuels has a harsh effect on the environment. Too much exploitation

of fossil fuels increases the level of green house gas content in the atmosphere,

resulting in global warming and a rise in the sea level.

It is not possible to completely reduce the consumption of fossil fuels. However,

some measures can be taken such as using electrical appliances wisely and not

wasting electricity. Unnecessary usage of water should be avoided. Public transport

system with mass transit must be adopted on a large scale. These small steps

may help in reducing the consumption of natural resources and conserving them.

Question 9:

What are the advantages and disadvantages of using a solar cooker? Are there

places where solar cookers would have limited utility?

Answer:

Solar cooker uses Sun’s energy to heat and cook food. It is inexhaustible and

clean renewable source of energy. It is free for all and available in unlimited

amount. Hence,operating a solar cooker is not expensive.

Disadvantage of a solar cooker is that it is very expensive. It does not work without

sunlight. Hence, on cloudy day, it becomes useless.

The places where the days are too short or places with cloud covers round the year,

have limited utility for solar cooker.

Question 8:

What are the qualities of an ideal source of energy?

Answer:

An ideal source of energy must be:

I. Economical

II. Easily accessible

III. Smoke/pollution free

IV. Easy to store and transport

V. Able to produce huge amount of heat and energy on burning

Question 7:

On what basis would you classify energy sources as

(a) renewable and non-renewable?

(b) exhaustible and inexhaustible?

Are the options given in (a) and (b) the same?

Answer:

(a) The source of energy that replenishes in nature is known as renewable

source of energy. Sun, wind, moving water, bio-mass, etc. are some of the

examples of renewable sources of energy.

The source of energy that does not replenish in nature is known as non-renewable

source of energy. Coal, petroleum, natural gas, etc. are some of the examples of

non-renewable sources of energy.

(b) Exhaustible sources are those sources of energy, which will deplete and

exhaust after a few hundred years. Coal, petroleum, etc. are the exhaustible

sources of energy.

Inexhaustible resources of energy are those sources, which will not exhaust in

future. These are unlimited. Bio-mass is one of the inexhaustible sources of

energy.Yes. The options given in (a) and (b) are the same.

Question 6:

What are the limitations of extracting energy from −

(a) the wind? (b) waves? (c) tides?

Answer:

(a) Wind energy is harnessed by windmills. One of the limitations of extracting

energy from wind is that a windmill requires wind of speed more than 15 km/h

to generate electricity. Also, a large number of windmills are required, which

covers a huge area.

(b) Very strong ocean waves are required in order to extract energy from waves.

(c) Very high tides are required in order to extract energy from tides. Also,

occurrence of tides depends on the relative positions of the Sun, moon, and

the Earth.

Question 5:

Compare and contrast bio-mass and hydro electricity as sources of energy.

Answer:

Bio-mass and hydro-electricity both are renewable sources of energy. Bio-mass

is derived from dead plants and animal wastes. Hence, it is naturally replenished.

It is the result of natural processes. Wood, gobar gas, etc. are some of the

examples of bio-mass.

Hydro-electricity, on the other hand, is obtained from the potential energy

stored in water at a height. Energy from it can be produced again and again.

It is harnessed from water and obtained from mechanical processes.

Question 4:

Compare and contrast fossil fuels and the Sun as direct sources of energy.

Answer:

Fossil fuels are energy sources, such as coal and petroleum, obtained from

underneath the Earth’s crust. They are directly available to human beings

for use. Hence, fossil fuels are the direct source of energy. These are

limited in amount. These are non-renewable sources of energy because

these cannot be replenished in nature. Fossil fuels take millions of years

for their formation. If the present fossil fuel of the Earth gets exhausted,

its formation will take several years. Fossil fuels are also very costly.

On the other hand, solar energy is a renewable and direct source of energy.

The Sun has been shining for several years and will do so for the next five

billion years. Solar energy is available free of cost to all in unlimited amount.

It replenishes in the Sun itself.

Question 3:

Most of the sources of energy we use represent stored solar energy. Which of the

following is not ultimately derived from the Sun’s energy?

(a) Geothermal energy

(b) Wind energy

(c) Nuclear energy

(d) Bio-mass

Answer:

(c) Nuclear energy is released during nuclear fission and fusion. In nuclear fission,

uranium atom is bombarded with low-energy neutrons. Hence, uranium atom splits

into two relatively lighter nuclei. This reaction produces huge amount of energy. In

nuclear fusion reaction, lighter nuclei are fused together to form a relatively heavier

nuclei. The energy required to fuse the lighter nuclei is provided by fission reactions.

This reaction produces tremendous amount of energy. These reactions can be carried

out in the absence or presence of sunlight. There is no effect of sunlight on these

reactions. Hence, nuclear energy is not ultimately derived from Sun’s energy.

Geothermal energy, wind energy, and bio-mass are all ultimately derived from solar

energy.

Geothermal energy is stored deep inside the earth’s crust in the form of heat energy.

The heating is caused by the absorption of atmospheric and oceanic heat. It is the

sunlight that heats the atmosphere and oceans.

Wind energy is harnessed from the blowing of winds. The uneven heating of the

earth’s surface by the Sun causes wind.

Bio-mass is derived from dead plants and animal wastes. Chemical changes occur in

these dead plants and animal wastes in the presence of water and sunlight. Hence,

bio-mass is indirectly related to sunlight.

Question 2:

Which of the following is not an example of a bio-mass energy source?

(a) wood                   (b) gobar gas

(c) nuclear energy       (d) coal

Answer:

(c) Bio-mass is a source of energy that is obtained from plant materials and

animal wastes. Nuclear energy is released during nuclear fission and fusion.

In nuclear fission, uranium atom is bombarded with low-energy neutrons.

Hence, uranium atom splits into two relatively lighter nuclei. This reaction

produces huge amount of energy. In nuclear fusion reaction, lighter nuclei

are fused together to form a relatively heavier nuclei. This reaction produces

tremendous amount of energy. Hence, nuclear energy is not an example of

bio-mass energy source. Wood is a plant material, gobar gas is formed from

animal dung, and coal is a fossil fuel obtained from the buried remains of

plants and animals. Hence, these are bio-mass products.

Question 1:

A solar water heater cannot be used to get hot water on

(a) a sunny day (b) a cloudy day

(c) a hot day (d) a windy day

Answer:

(b) A solar water heater uses solar energy to heat water. It requires bright and

intense sunlight to function properly. On a cloudy day, the sunlight reflects back

in the sky from the clouds and is unable to reach the ground. Therefore, solar

energy is not available for the solar heater to work properly. Hence, solar

water heater does not function on a cloudy day.

Question 2:

Give the names of two energy sources that you would consider to be exhaustible.

Give reasons for your choices.

Answer:

Two exhaustible energy sources are as follows:

(a) Coal: It is produced from dead remains of plants and animals that remain

buried under the earth’s crust for millions of years. It takes millions of years

to produce coal.

Industrialization has increased the demand of coal. However, coal cannot

replenish within a short period of time. Hence, it is a non-renewable or

exhaustible source of energy.

(b) Wood: It is obtained from forests. Deforestation at a faster rate has caused

a reduction in the number of forests on the Earth. It takes hundreds of years to

grow a forest. If deforestation is continued at this rate, then there would be no

wood left on the Earth. Hence, wood is an exhaustible source of energy.