Unlike acetylene, ethylene dissolves in concentrated sulphuric acid- why ?

Explanation

In the first step of the reaction with concentrated `H_(2)SO_(4)`, ethylene forms ethyl cation `(CH_(3)overset(oplus)(C)H_(2))` and acetylene forms a vinyl cation `(CH_(2) = overset(oplus)(C)H)` by accepting a `H^(oplus)` ion. Since vinyl cation is less stable than ethyl cation, in case of acetylene, the first step (rate-determining step) of the reaction does not occur easily. Thus, unlike ethylene, acetylene fails to dissolve in concentrated `H_(2)SO_(4)`.