The major product '$B$' in the below mentioned reaction is:
$CH_3-CH(Br)-CH_3 \xrightarrow[\Delta]{\text{Alc. KOH}} A \xrightarrow[\text{Peroxide absent}]{\text{HBr}} B$

At $30\,^\circ C$,the rate of reaction between $2$-bromobutane and $OH^-$ in $75\%$ ethanol and $25\%$ water is given by: $\text{Rate} = 3.20 \times 10^{-5} [2\text{-bromobutane}][OH^-] + 1.5 \times 10^{-6} [2\text{-bromobutane}]$. If $[OH^-] = 1.0\,M$,what percentage of the reaction proceeds via the $S_N2$ mechanism?

An isomer of $C_5H_{12}$ on reaction with $Br_2 / \text{light}$ gave only one isomer $C_5H_{11}Br(X)$. Reaction of $X$ with $AgNO_2$ gave $Y$ as the major product. What is $Y$?

When chloroform is exposed to air and sunlight,it gives ...... .

When $HNO_3$ is reacted with $ . . . . . . $,chloropicrin is formed.

What is the primary product of an $S_N1$ reaction on an optically active substance?