3. Substitution reactions:

The reactions in which one or more hydrogen atoms of a molecule are replaced and by some other atoms or groups are called substitution reactions. The substitution reaction in which one or more hydrogen atoms are replaced by an equal number of halogen atoms is called halogenations. Saturated hydrocarbons (alkanes) give substitution reactions.

Methane reacts with chlorine (or bromine) in the presence of sunlight or a halogen-carrier to give haloalkenes in which one or more H-atoms are replaced by equal number of halogen atoms.

4. Action with steam:

Methane gives hydrogen when mixed with steam and the mixture is passed over nickel supported on alumina heated to 1000k.

5. Pyrolysis :

When heated to about 1300 k, methane gets decomposed to give carbon black and hydrogen