ICSE Class 7 Answered
Nitrogen and Oxygen are the two major gases present in the atmosphere.
Carbon dioxide, argon, helium, hydrogen and ozone are present in the atmosphere in small quantities.
Nitrogen constitutes 78% of the total volume of the atmosphere.
Oxygen is the second most available gas in the atmosphere and is also known as the life giving gas as it is required by human beings and animals for respiration.
Gases like argon, carbon dioxide, and water vapour constitute the remaining one percent of the volume of the atmosphere.
Carbon dioxide, present in atmosphere in small quantities, is used by plants for making food. The quantity of carbon dioxide remains constant in the atmosphere. However, its amount may increase due to the burning of fuels like coal and oil. The increase in the level of carbon dioxide adversely affects the weather conditions and the climate of the Earth.