Name : Four sources of surface water .

Name two sources of sound.

State two sources each of a surface water b. underground water.

Which of the following is not a source of surface water?

Name : Three major sources of natural water

Name : Two underground sources of water.

A point source of light is placed 4 m below the surface of water of refractive index (5)/(3). The minimum diameter of a disc, which should be placed over the source, on the surface of water to cut off all light coming out of water is

Name two main sources of nuclear radiations. How are the nuclear radiations harmful ?

Name two sources of electricity.

Name the following : Various sources of carbon.

Name any two source organisms of agar. List any four areas in which agar has wide application