Explain with an example.

Explanation

The reaction in which the place of one type of atom or group of atoms in a reactant is taken by another atom or group of atoms is called Substitution reaction.
`CH_(4)+Cl_(2) overset("sunlight")to CH_(3)-Cl+HCl`
`CH_(3)Cl+Cl_(2)overset("sunlight")to CH_2Cl_(2)+HCl`
`CH_(2)Cl_2+Cl_(2)overset("sunlight")to CHCl_(3)+HCl`
`CHCl_3+Cl_(2)overset("sunlight")to C Cl_(4)+HCl`
(ii) When a carbon compound combines with another compound to form a product that contains all the atoms in both the reactants, it is called an addition reaction. For example When ethene is heated with bromine, bromine gets added to ethene to form ethylene dibromide.
`underset("Ethene")(H-overset(H)overset(|)(C))=overset(H)overset(|)(C)-H+underset("Bromine")(Br-Br )overset(triangle)to H-underset("Ethylene dibromide")(underset(Br)underset(|)overset(H)overset(|)(C)-underset(Br)underset(|)overset(H)overset(|)(C)-H)`