Q4. What are non metals?
Ans. They are non malleable, non ductile and bad conductor of heat and electricity. They possess low melting point and boiling point. They are brittle( break easily when force  is applied). Example: Carbon, Sulphur, Phosphorus, Nitrogen, Oxygen, Iodine etc.

On the basis of chemical reaction non metals are defined as follows:
Non metals are those elements which form negative ions (anions) by gaining electrons. Show non metals are known as electro-negative elements.