Write the name and general formula of a chain of hydrocarbons in which an addition reaction with hydrogen can take place. Stating the essential conditions required for an addition reaction to occur, write the chemical equation giving the name of the reactant and the product of such a reaction.

The chain of hydrocarbons in which an addition reaction with hydrogen can take place are alkene (CnH2n) and alkyne (CnH2n−2). The essential condition required for an addition reaction to occur is that the hydrocarbons should contain double or triple bonds, i.e., they should be unsaturated hydrocarbons.

Reaction of alkene: Addition of hydrogen to ethene produces ethane (alkane)
CH2=CH2 + H2 Ni → CH3−CH3

Reaction of alkyne: Addition of hydrogen to ethyne produces ethane (alkane). 2 molecules of hydrogen are required in this reaction.
CH≡CH + 2H2 Ni → CH3−CH3