Answer
The complete alkene addition reaction is as follows:
Work Step by Step
Here, 2-butene (Alkene) participate in addition reaction with Chlorine molecule and as a consequence, double bond of 2-butene breaks down to single bond and two Chlorine atom is added to $C_{2}$ and $C_{3}$ carbon. That's why this is called Alkene addition reaction. Unsaturated hydrocarbons (Alkenes and Alkynes) participate in such reaction due to presence of double or triple bond in them.
