What makes the wind Blow?

(a)  

(a)   is seen on very cold morning in winter in some parts of North india.

The process by which water changes to water vapour in the heat of a sun is called

(a)   .

(a)   water is harmful to drink.

The living and non-living things that make up the surrounding of living thing

is called (a)   .

The process by which fertile soil is washed away by wind or rain is called

(a)   .

Harmful gases mixed with water drops to form dangerous substance is called

(a)   .

Harmful gases mixed with water drops leads to (a)   .

The addition of harmful substances to land,air and water is called (a)   .

Smoke given out by vehicles and factories causes (a)   .

The waste thrown out from houses and factories to the river,seas and lakes causes

(a)   pollution.

Drinking of polluted water can cause diseases such as _____,_____

and_______.

(a)  

_______,______ and ______ are causesby the condensation of water vapour near or on the ground.

(a)  

Which substance is added to the polluted water to remove dirt and kill germs?

(a)  

Three-forths of the Earth's surface is coverd with (a)   .

The process by which water vapour changes back to water is called (a)