Question

Give one word for the following.

The percentage of this gas in air is 21%.

Answer 1

• Oxygen is a gas that has a percentage of 21 in the atmosphere.
• Oxygen plays a vital role as living organisms need oxygen for respiration.
• Respiration: It is the process in which living organisms use oxygen for the oxidation of glucose and in this process, the energy which is released is stored for day-to-day work. The by-product of respiration is carbon dioxide which is then released by organisms in the environment.