Hardening of oil is done by

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

What is the major product of the following reaction?
$1\text{-methylcyclohexene} + Br_2 \xrightarrow{H_2O} ?$

Pent-$1$-ene reacts with diborane to form $X$. $X$ on oxidation using $H_2O_2$ in the presence of aqueous $NaOH$ gives $Y$. Compound $Y$ is

An optically active compound $A$ with molecular formula $C_8H_{14}$ undergoes catalytic hydrogenation to give a meso compound. The structure of $(A)$ is:

$CH_3-CH_2-CH=CH_2 \xrightarrow[CCl_4]{Br_2} \text{Product}$