Hey sanjeev,

Alkenes are generally prepared through beta elimination reactions, in which two atoms on adjacent carbon atoms are removed, resulting in the formation of a double bond.

Comman reactions of alkenes are.

1. Hydrogenation of alkenes

2. Alkenes with bromine

3. Alkenes with concentrated sulphuric acid

4. Alkenes with hydrogen halide.

I hope you get your answer, for more querries you can reply back to us.