Preparation of looking mirrors involves the use of

The major product formed in the following reaction is:

The same product $(A)$ is formed in both of the following reactions:
$1. PhMgBr + CH_3-CN \xrightarrow{H_3O^{+}} (A)$
$2. Ph-COOH \xrightarrow{(1) \text{ excess } CH_3Li, (2) H_3O^{+}} (A)$
Identify product $(A)$.

The alkaline $CuSO_4$ solution containing sodium potassium tartrate does not react with:

Rank the following compounds in order of increasing value of the equilibrium constant for hydration,$K_{hyd}$. (smallest value first).
$1$: Cyclobutanone
$2$: Cyclopropanone
$3$: Di-tert-butyl ketone

For the sequence of reactions $A$ $\xrightarrow{C_2H_5MgI} B$ $\xrightarrow{H_2O / H^{+}} \text{tert-pentyl alcohol}$. The compound $A$ in the sequence is