Which of the following compounds undergoes haloform reaction?

$(A) Ph-CH(OH)-CHO \xrightarrow[H_2O]{HO^-} (B)$; $(A)$ and $(B)$ are isomers and isomerization is effectively carried out by a trace of base. Identify $(B)$.

Which of the following can be used to convert benzophenone into benzene?

Consider the following reaction sequence:
$4\text{-aminobenzonitrile}$ $\xrightarrow[(ii) H_2O]{(i) AlH(i-Bu)_2} 'A'$ $\xrightarrow[dil. NaOH, \Delta]{CH_3CHO} B$
The product $B$ is?

Clemmensen reduction of a ketone is carried out in the presence of

Formaldehyde can be distinguished from acetaldehyde by the use of