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

$1$-chlorobutane on reaction with alcoholic potash gives

Vicinal and geminal dihalides can be distinguished by using:

Which among the following compounds undergoes $SN^2$ reaction most rapidly?

The correct order of $C-X$ bond polarity is:

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