Question

1. What is composition of air ?
2. Which gas in the atmosphere is essential for repiration ?

Answer 1

Answer:

and of question no. two is O2 and CO2.

O2 for human beings and aquatic organisms and CO2 for plants

Answer 2

Answer:

Nitrogen and oxygen are two gases which make up the bulk of the atmosphere. Carbon dioxide, helium, ozone, argon and hydrogen are found in lesser quantities. Apart from these gases, tiny dust particles are also present in the air.