What is the structure of $C$?

Which of the following does not form a stable hydrate on addition of $H_2O$?

Methyl ketone can be oxidized using the haloform reaction. The oxidized product (carboxylate ion) has $:-$

$CH_3CHO$ $\xrightarrow[5\,^{\circ}C]{10\%\,NaOH}$ $\xrightarrow[\Delta]{}$ $\xrightarrow[Ni]{H_2} (A)$; Product $(A)$ of the reaction is

Fehling solution reacts with $HCHO$ to form a precipitate of which color?

In the given reaction sequence,$Z$ is a mixture of alcohol and acid. The reaction for the conversion of $Y$ to $Z$ is:
$CH_3CH_2OH$ $\xrightarrow[443 \ K]{\text{Conc. } H_2SO_4} X$ $\xrightarrow[(2) \ Zn/H_2O]{(1) \ O_3} Y$ $\xrightarrow[(ii) \ H^+]{(i) \ \text{Conc. } NaOH} Z$