Chapter 14: Natural Resources

How do fossil fuels cause air pollution?

Soln:

Fossil fuels like petrol, diesel and kerosene releases oxide of Sulphur, nitrogen and carbon. Sulphur and Nitrogen oxides cause acid rain.

Burning fossil fuels release carbon monoxide which increases the carbon-di-oxide in the atmosphere which will affect living organisms.

Burning of fuels increases the amount of suspended particles in the air which reduces visibility.

52. What are the causes of water pollution? Discuss how you can contribute in reducing water pollution.

Soln:

Causes of water pollution are given below

1. Chemical Fertilizers and pesticides consist of poisonous chemical which reaches the water body to turn water into toxic.
2. Dumping of sewage directly into water bodies
3. Release of industrial effluents into water resources.

Below are the steps we can take to reduce water pollution

1. Stop connecting sewage lines directly to water bodies.
2. Avoiding throwing garbage and other domestic waste into the water resource.
3. Prevent dumping of toxic chemical into water body.
4. Avoid washing of clothes near water bodies.

53. 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?

Soln:

Infrared radiation emitted by the sun can pass the transparent glass and increases the temperature inside the car. These radiations have smaller wavelength than the radiations emitted by the car. For these waves, transparent glass remain opaque further increasing the temperature.

54. Justify “Dust is a pollutant”?

Soln:

Dust is a fine powder of tiny earth particles and waste matter. It is carried to the atmosphere by wind, dust causes allergy in humans and affects plant growth by blocking the stomata on the leaf surface. Dust also carries toxic substance from the environment to pollute the water bodies affecting the aquatic life.

55. Explain the role of the Sun in the formation of soil.

Soln:

Sunlight heats the rock in the afternoon which results in the expansion of rock. When it cools down in the night contraction takes place which is not at the rate of expansion. Because of this difference in the rate of expansion and contraction rock get cracked to form small rock particles.

56. Carbon dioxide is necessary for plants. Why do we consider it as a pollutant?

Soln:

Carbon dioxide is considered a pollutant because it is a green-house gas which is responsible for global warming. This results in a change of earth’s climate. Along with that excess CO₂ is harmful to the plants. Increased CO2 levels change physiology, growth and chemistry of plants. High CO2 concentration also causes suffocation, hard breathing and choking issues.