question_answer

Analyse the following reaction and identify the nature of \[A\] and \[B\] [Kerala CET 2005]                                        \[B\underset{hv}{\mathop{\xleftarrow{HBr}}}\,\] \[\xrightarrow{HBr}A\]

A) Both A and B are  

B) Both A and B are

C) A is   & B is  

D) A is   & B is

E) A is  & B is

Correct Answer: C

Solution :

                   \[\xrightarrow{HBr}A\]                    Formation of A is a electrophilic addition reaction                    (i)  \[HBr\to {{H}^{+}}+B{{r}^{-}}\]                    (ii)           \[+{{H}^{+}}\to \overset{+}{\mathop{{{C}_{6}}{{H}_{5}}CHC{{H}_{3}}}}\,\]                                                                                                                        \[\underset{hv}{\mathop{\xrightarrow{HBr}}}\,\,B\]                    Formation of B is a free radical addition reaction            (i) \[HBr\xrightarrow{hv}\overset{\bullet }{\mathop{H}}\,+\overset{\bullet \,\,\,}{\mathop{Br}}\,\]            (ii)             (iii)