Atoms and Molecules — Science STD 9 — Question

In which medium sound travels faster: air or hydrogen?

State whether colloidal solutions are homogeneous or heterogeneous.

Name the process which can be used to recover salt from and aqueous salt solution.

Name two other sea food items except fish.

Name two potassic fertilizers.

Name two ecological problems which are caused by application of synthetic chemicals to crop fields.

The process of supplying _______ to crops in the fields by means of canals, reservoirs, wells, river valley systems and river lift systems is known as _______.

What is the nature of sound waves in air?

Why water should be used judiciously?

Give the names and symbols of five familiar substances which you think are elements.