'Atoms of the same element or different elements combine to form a molecule'.
Give two examples each of
a] Atoms of the same element
b] Atoms of different elements combining to form a molecule.

Explain the term - 'atomicity'. Give reasons why - 

a] Helium is considered monoatomic, but hydrogen a diatomic molecule.

b] Ozone is considered triatomic, but phosphorus a tetratomic molecule.

State the atomicity of neon.

'A radical takes part - unsplit in a chemical reaction retains its identity in reactions'. With reference to the radical - a] Ammonium b] Bisulphate c] Carbonate - state the group of atoms present in each radical.