Question

The only alkene which gives primary alkyl halides on hydrohalogenation is:

• A. $C_2{H}_4$
• B. $C_3{H}_6$
• C. $C_4{H}_8$
• D. $C_5{H}_{10}$

Answer 1

The correct option is A $C_2{H}_4$

All except $C_2{H}_4$ would form a secondary carbocation as an intermediate leading to the formation of a secondary alkyl halide.

Ethene is symmetrical alkene having two carbons so the addition of halogen acid ($HBr$) will give primary alkyl halide.

Option A is correct.