Which of the following statements are correct?

AThe heat of hydrogenation of (E)-but-2-ene is smaller in magnitude than that of (Z)-but-2-ene
BHydroboration-oxidation of 1-methylcyclohexene gives trans-2-methylcyclohexan-1-ol
COxymercuration-demercuration of 3,3-dimethylbut-1-ene gives 3,3-dimethylbutan-2-ol without skeletal rearrangement
DAddition of $Br X_{2}$ to cyclohexene in $CCl X_{4}$ gives mainly cis-1,2-dibromocyclohexane

Answer: A, B, C

B and H add syn: B goes to

C X_{2}

and H to

C X_{1}

on the same face, so the new OH and the methyl on

C X_{1}

are trans. The mercurinium ion does not allow a carbocation rearrangement, so Markovnikov OH appears on

C X_{2}

. The E alkene is more stable, so it releases less heat on hydrogenation. Bromination is anti, giving trans-1,2-dibromocyclohexane.