Which of the following halides will give $S_N 1$ reaction fastest?

The reaction for the preparation of ethene from ethyl chloride is known as......

The major product $(A)$ of the following reaction is:

Match the reactions given in Column-$I$ with their names given in Column-$II$.

Column-$I$	Column-$II$
$(i)$ $R-Cl + NaI \xrightarrow{\text{dry acetone}} R-I + NaCl$	$(a)$ Swarts reaction
$(ii)$ $CH_3-Br + AgF \xrightarrow{\Delta} CH_3-F + AgBr$	$(b)$ Wurtz reaction
$(iii)$ $R-X + Mg$ $\xrightarrow{\text{dry ether}} R-Mg-X$ $\xrightarrow{H_2O} RH + Mg(OH)X$	$(c)$ Finkelstein reaction
	$(d)$ Grignard reaction

Which $Cl$ atom is most susceptible to be attacked by aqueous $KOH$?

$A$ bromoalkane $X$ reacts with magnesium in dry ether to form compound $Y$. The reaction of $Y$ with methanal followed by hydrolysis yields an alcohol having molecular formula $C_{4}H_{10}O$. The compound $X$ is