Question

what is a molecule?how are molecules of an element different from molecules of a compound ?Explain with the help of 4 examples each .

Answer 1

A molecule is group of atoms (it can either be in an element or a compond ) 
.
Molecule of an element has identical atoms Eg N2. it has two atoms of nitrogen.

molecule of a compund has diffirent atoms. Eg HCl. It has  an atom of hydrogen and an atom of chlorine

Answer 2

molecules are the smallest particles of a pure substance that can exist independently and are made up of 2 or more atoms.
molecule are 2 types.