Question

please give the answer and reason behind this ​

Answer 1

Answer:

repulsion due to big methyl grp compine with markonikove rule

Answer 2

Answer:

Addition of HBr to alkene involves the formation of carbocation intermediate. Thus anything which increases the electron density around the double bond will ease the reaction.

(Refer to Image)

The carbocation is stabilized by the presence of alkyl group due to +I effect.

Hence the addition of HBr is easiest with (CH3)2C=CH2