A sodium salt is warmed with conc. $H X_{2} SO X_{4}$ and the gas mixture ( $H X_{2} C X_{2} O X_{4} CO + CO X_{2} + H X_{2} O$ for the acid formed) is passed through conc. NaOH solution. The gas that leaves the NaOH, and the moles of it from 1 mol oxalate, are respectively

Answer: C

Conc.

H X_{2} SO X_{4}

dehydrates oxalic acid to equal moles of CO and

CO X_{2}

. NaOH absorbs acidic

CO X_{2}

, leaving CO that burns with a blue flame. 1 mol oxalate gives 1 mol CO.