Addition of $Br_2$ to $trans-2-butene$ would give a product which is

What is the product formed when $trans-2$-butene reacts with $D_2$ in the presence of a $Ni$ catalyst?

What is the correct order of stability for the following alkenes?

Among the following, the compound having conjugated double bonds is

But$-2-$ene on reaction with alkaline $KMnO_4$ at elevated temperature followed by acidification will give:

What will be the product $B$ formed in the following reaction sequence?
$CH_3CH_2CH_2OH$ $\xrightarrow{PCl_5} A$ $\xrightarrow{alc. KOH} B$