If (C) contains a carbonyl group in it, then how many methyl group(s) is/are attached to its cyclic ring?

In the following reaction sequence, structures of $\mathrm{A}$ and $\mathrm{B}$ are, respectively

Fill up the blank:

$\mathrm{NaOH}+{\mathrm{H}}_2\mathrm{S}\to$ _____$+{\mathrm{H}}_2\mathrm{O}$  (Give the name of the compound formed)

The major product in the following reaction is :

The major product of the following reaction is :

The major products of the following reaction are :

KI in acetone, undergoes S_N2 reaction with each of P, Q, R and S. The rates of the reaction vary as

In the following reaction the major product is

Here, $\mathrm{Z}$ is: