Why do terrestial life forms require fresh water?

(i) Define the term 'smog'.
(ii) Name two types of diseases caused by regularly breathing the polluted air.

What are the two factors that cause changes in our atmosphere?

What are the two ways in which carbon dioxide is fixed to keep its percentage almost constant?

What are the two things which are essential for all forms of life on the earth?

What is the role of the atmosphere in climate control?

Increase in concentration of carbon dioxide in the atmosphere may cause ........ effect.

Various man-made compounds such as ........ cause depletion of ozone layer.

We need to ........ our natural resources and use them in a .......... manner.

.............. of air, water and soil affect the quality of life and ......... the biodiversity.

............... of water from water bodies and subsequent ......... give us rain.

Nitrogen fixing bacteria cannot fix N₂ in presence of 

Which of the following does not contain nitrogen?

Which one of the following are not involved in nitrogen fixation?

Bits of decayed living organisms in soil is called

The outer crust of the earth is called

The main cause of depletion of ozone layer is excessive use of

Ozone hole was first observed over

Most of the water on the earth surface is found in

The surface of the earth covered with water is 

Humus causes the soil to