The reaction $CH_3CHO \xrightarrow[Zn(Hg) / \text{Conc. } HCl]{[H]} CH_3CH_3$ is:

The final product of the following reaction contains:
$CH_3 - C \equiv C - CH_2 - COCl \xrightarrow[BaSO_4]{H_2 - Pd}$

The given reaction is: $C_6H_5-CHO + C_6H_5-CHO \xrightarrow{Na_2[Fe(CO)_4]} C_6H_5-COOCH_2-C_6H_5$

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.

In the reaction sequence: $CH_2OH-CHOH-CH_2OH$ $\xrightarrow{KHSO_4/\Delta} (X)$ $\xrightarrow{(C_2H_5O)_3Al/\Delta} (Y)$,$(Y)$ will be:

Which of the following is not an $o, p-$ directing group?