In the catalytic reduction of hydrocarbons,which catalyst is mostly used?

Provide the structural formula for $2$-methyl-$2$-butene.

The product $(P)$ in the given reaction is:

The number of alkene$(s)$ which can produce $2-butanol$ by the successive treatment of $(i)$ $B_{2}H_{6}$ in tetrahydrofuran solvent and $(ii)$ alkaline $H_{2}O_{2}$ solution is:

In the following reaction,$A$ and $B$ respectively are
$A \xrightarrow{HBr} C_2H_5Br \xrightarrow{B} A$

In the following reaction $CH_3-C(CH_3)_2-CH=CH_2 \xrightarrow{H_2O/H^{+}} A \text{ (major)} + B \text{ (minor)}$,the major product $A$ is: