Why is it essential for all living beings? State the cause for the depletion of this gas.

13 Gas A, found in the upper layers of the atmosphere, is a deadly poison but is essential for all living beings. The amount of this gas started declining sharply in the 1980s.
b. Why is it essential for all living beings? State the cause for the depletion of this gas.

Ans : b. Ozone shields the surface of the earth / protects living organisms from ultraviolet (UV) radiation released by the sun.

Chlorofluorocarbons (CFCs) (½ mark) which are used as refrigerants / in fire extinguishers lead to depletion of ozone layer