$1,2-dichlorocyclopentane$ $\xrightarrow{1 \text{ equivalent } Mg, \text{ ether}} X$ $\xrightarrow{D_2O} Y;$
$Y$ is:

The major product of the following reaction is:

Which of the following compounds reacts with $KCN$ to form a cyanide?

When $3-$methylbutan$-2-$ol is treated with $HBr$,the following reaction takes place:
$CH_3-CH(CH_3)-CH(OH)-CH_3 \xrightarrow{HBr} CH_3-C(Br)(CH_3)-CH_2-CH_3$
Give a mechanism for this reaction.
(Hint : The secondary carbocation formed in step $II$ rearranges to a more stable tertiary carbocation by a hydride ion shift from $3^{rd}$ carbon atom.)

Among the following chlorides,the compounds which will be hydrolysed most easily and most slowly in aqueous $NaOH$ solution are respectively:
$1$. Methoxymethyl chloride $(CH_3OCH_2Cl)$
$2$. Benzyl chloride $(C_6H_5CH_2Cl)$
$3$. Neopentyl chloride $((CH_3)_3CCH_2Cl)$
$4$. Propyl chloride $(CH_3CH_2CH_2Cl)$

Identify the product $A$ in the following reaction: $C_2H_5Br + \text{aq. } KOH \rightarrow A + KBr$