The major product $(A)$ is:

Toluene (excess) undergoes the following sequence of reactions:
$(i)$ $CrO_2Cl_2, CS_2$
(ii) $H_3O^+$
(iii) $NaHSO_3$
After filtration,a residue $(A)$ is obtained. This residue $(A)$ reacts with $dil. \ HCl$ to form compound $(B)$.
Identify the structures of residue $(A)$ and compound $(B)$ respectively.

An aromatic compound $A$ (Molecular formula $C_{8}H_{8}O$) gives a positive $2,4-DNP$ test. It gives a yellow precipitate of compound $B$ on treatment with iodine and sodium hydroxide solution. Compound $A$ does not give Tollen's or Fehling's test. On drastic oxidation with potassium permanganate,it forms a carboxylic acid $C$ (Molecular formula $C_{7}H_{6}O_{2}$),which is also formed along with the yellow compound in the above reaction. Identify $A, B$ and $C$ and write all the reactions involved.

The conversion shown in the image can be achieved by:

The major product in the following reaction sequence is

Which of the following will form a stable hydrate?