Question

why unsaturated hydrocarbons show addition reaction but saturated hydrocarbons not?

Answer 1

Unsaturated hydrocarbons show addition reaction because they contain multiple bonds (that is double and triple bonds). These multiple bonds consist of pi bonds which can be easily broken. For example, unsaturated hydrocarbons add hydrogen in the presence of catalysts such as palladium or nickel to give saturated hydrocarbons.

Answer 2

Addition reaction is a type of reaction in which two or more molecules combine with each other to form a single substance. ... Substitution reaction does not add any atom to the hydrocarbon because it takes place only in saturated hydrocarbons(containing only single bonds).