Heat of hydrogenation of cyclohexene $({\rm{one}}\,\,C = C\,\,{\rm{bond}})$ is $ - 28.4\,\,k.cal.mo{l^{ - 1}}$. Hence,heat of hydrogenation of benzene $({\rm{three}}\,\,C = C\,\,{\rm{bonds}})$ should be

$ - 49.3\,\,k.cal.mo{l^{ - 1}}$

$ - 35.9\,\,k.cal.mo{l^{ - 1}}$

NEET UG CHEMISTRY MCQ: HYDROCARBONS

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Heat of hydrogenation of cyclohexene

(\mathrm{one}\,\,C = C\,\,\mathrm{bond})

- 28.4\,\,k.cal.mo{l^{ - 1}}

. Hence,heat of hydrogenation of benzene

(\mathrm{three}\,\,C = C\,\,\mathrm{bonds})

should be

View answer and explanation

Correct option: A

- 85.2\,\,k.cal.mo{l^{ - 1}}

Option A is correct because the addition of HBr to 3-phenylpropene follows Markownikoff's rule, and also considers the stability of the carbocation intermediate. The more stable carbocation is benzylic and secondary, leading to the major product.

NEET UG CHEMISTRY MCQ: HYDROCARBONS

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