Cannizzaro reaction between formaldehyde molecules involves the formation of

Total number of nucleophiles from the following is $:-$ $NH_3, PhSH, (H_3C)_2S, H_2C=CH_2, \stackrel{\ominus}{O}H, H_3O^{\oplus}, (CH_3)_2CO, CH_3CH=NCH_3$

Which among the following colours is obtained in Schiff test of aldehydes?

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.

The product $(P)$ of the below reaction sequence is:

Which pair of reactant compounds may be used to make the given acetal?