Question 1

Which gas is found in the highest quantity in the atmosphere?

Accepted Answer

Nitrogen is the most plentiful gas in the air (about 78%). When we breathe, we take some amount of nitrogen into our lungs and exhale it. But plants need nitrogen for their survival. They can not take nitrogen directly from the air. Bacteria, that live in the soil and roots of some plants, take nitr

Question 2

Which gas is released by green plants during photosynthesis?

Accepted Answer

Oxygen is the second most plentiful gas in the air. Humans and animals take in oxygen from the air. Green plants produce oxygen during photosynthesis. In this way, humans and animals consume oxygen and release carbon dioxide, while plants take in carbon dioxide and release oxygen, thus maintaining a

Question 3

Which layer of the atmosphere is closest to the Earth's surface?

Accepted Answer

The troposphere is the most important layer of the atmosphere. Its average height is 13 km. The air we breathe exists here. Almost all weather phenomena like rainfall, fog and hailstorm occur in this layer.

Question 4

Which layer of the atmosphere contains the ozone layer?

Accepted Answer

The stratosphere lies above the troposphere. It extends up to a height of 50 km. This layer is virtually free from clouds and associated weather phenomenon, making conditions most ideal for flying aeroplanes. One important feature of stratosphere is that it contains a layer of ozone gas.

Question 5

In which layer do meteorites burn up upon entering from space?

Accepted Answer

The mesosphere is the third layer of the atmosphere. It lies up to the height of 80 km. Meteorites burn up in this layer on entering from space.

Air — NCERT Class 7 Social Science Important Questions & Revision Notes