An organic compound " x " where molar ratio of C, O and H are...

Given the molar ratio of C, O, and H in compound $x$ is equal, the empirical formula is $CHO$.

Empirical mass $= 12 + 1 + 16 = 29$ g mol$^{-1}$.

Since the molar mass of $x$ is $58$ g mol$^{-1}$, the molecular formula is $(CHO)_2$ or $C_2H_2O_2$.

The structure of $x$ is glyoxal, $OHC-CHO$.

Treatment of glyoxal with $50\%$ KOH under reflux results in an intramolecular Cannizzaro reaction. One aldehyde group is oxidized to a carboxylate ion, and the other is reduced to a primary alcohol.

$OHC-CHO \xrightarrow{50\% \text{ KOH}} HOCH_2-COO^{-}K^{+}$

Subsequent acidification yields glycolic acid ($y$).

$HOCH_2-COO^{-}K^{+} \xrightarrow{H^{+}} HOCH_2-COOH$

The structure of $y$ is $HO-CH_2-COOH$.

Answer: $O = C - OH, \, CH_2 - OH$ (with C-C bond)