Manipur Board Class 7 Social Science Chapter 3 Air Question Answer Solution. We have uploaded this page so that students of Manipur State Board can learn online by their smartphone / laptop or other devices.
Manipur Board Class 7 Social Science Chapter 3: Air
- Board – Board of Secondary Education, Manipur.
- Class – 7
- Subject – Social Science
- Topic – Exercise Solution / Notes / Question Answer.’
1.) Answer the following in a word :
(a) The lowest layer of the atmosphere – Troposphere.
(b) The layer which sends back radio signals to the earth – Ionosphere.
(c) The incoming solar radiation received by the earth – Insolation.
2.) Answer the following questions in about 30 words each :
(a) Mention the uses of the two most plentiful gases of the atmosphere.
Ans- The uses of the two most plentiful gases of the atmosphere i.e- Oxygen and Nitrogen are as follows:
Nitrogen is the most plentiful gas. It occupies 78% of the total volume. When we inhale, we take some amount of nitrogen into our lungs. Nitrogen is vital for plant life. Oxygen makes up about 21% of the air by volume. Human beings and animals need oxygen to breathe. Green plants produce oxygen. In this way, oxygen content in the air remains constant. Therefore, we should plant new trees before we cut others.
(b) Give the significance of the ozone layer to human beings.
Ans- Ozone is found in upper stratosphere and mesosphere. Ozone layer absorbs ultraviolet rays from the sun. If these rays were to reach the earth, it would be dangerous for our life.
(c) How is the atmosphere heated ?
Ans- The atmosphere does not get heated directly by the sun’s rays. It absorbs very little of the solar radiation. From the ground surface, the heat is transferred to atmosphere through the process of radiation, conduction, convection and advection.
(d) Name the main pressure belts on the surface of the earth.
Ans-The main pressure belts on the earth’s surface are Equatorial Low Pressure Belt, Subtropical High Pressure Belts, Subpolar Low Pressure Belts and Polar High Pressure Belts.
3.) Choose the correct answer :
(i) The process of conversion of water vapour into water droplets is known as – (b) Condensation.
(ii) The condition of the atmosphere at a particular place and time is called – (a) Weather.
(iii) Based on latitudinal location, Manipur belongs to – (a) Tropical zone.
4.) Mark True or False against the following statements :
(a) The tropopause is the boundary between the stratosphere and the mesosphere- False
(b) Air pressure is measured by an instrument called thermometer – False
(c) Plant absorbs carbon dioxide to make its food -True
(d) Water vapour is absent in the lower atmosphere- False
(e) Torrid zone is the hottest part of the earth- True