The rate of $S_{N}2$ reaction is maximum when the solvent is

On monochlorination of $2-$methylbutane,the total number of chiral compounds is

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$ :
Assertion $(A)$ : $S_N2$ reaction of $C_6H_5CH_2Br$ occurs more readily than the $S_N2$ reaction of $CH_3CH_2Br$.
Reason $(R)$ : The partially bonded unhybridized $p$-orbital that develops in the trigonal bipyramidal transition state is stabilized by conjugation with the phenyl ring.
In the light of the above statements,choose the most appropriate answer from the options given below:

The major product of the following reaction is:

Which of the following alkyl halides is the fastest to undergo dehydrohalogenation with a base?

Consider the following reaction,
$C_2H_5Cl + AgCN \xrightarrow{EtOH / H_2O} \underline{X} \text{ (major)}$
Which one of the following statements is true for $\underline{X}$?
$(I)$ It gives propionic acid on hydrolysis
$(II)$ It has an ester functional group
$(III)$ It has a nitrogen linked to ethyl carbon
$(IV)$ It has a cyanide group