(A) Addition of HI takes place by the formation of
1∘ and
2∘ carbonium ion.
2∘ carbonium ion being more stable will form major product, i.e. 2 -iodopropane.
(B) The reaction of bromine with 1 -phenylethane proceed with formation of free radical.
2∘ free radical being more stable than
1∘ free radical, will form the product as 1-bromo-1-phenylethane.
(C) Reaction of HBr to an alkene follows Markownikoff rule. So, the product will be 1-bromo-1-phenylethane.
Note : Markownikoff's rule states that, electron rich component adds to carbon atom with less number of hydrogen atoms.
Hence, the correct match is A-III, B-IV, C-IV. The reactions are :