Which of the following compounds has the fastest $S_N2$ reaction rate?

Rate of $S_N2$ reactions depends on :

What is produced when toluene is heated with chlorine in the presence of light and in the absence of a halogen carrier?

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

Sodium tertiary butoxide on reaction with methyl bromide produces the product $P$.
Sodium methoxide upon reaction with tertiary butyl bromide generates the product $Q$.
The products $P$ and $Q$ are

Which of the following reacts most rapidly with ethanol?