Question

Two organic compounds (A) and (B) have same empirical formula CH${}_2$O. Vapour density of (B) is twice the vapour density of (A). (A) reduces Fehling solution but does not react with NaHCO${}_3$. Compound (B) neither reacts with NaHCO${}_3$ nor reduces Fehling solution. What are (A) and (B) ? Also report an isomer of (B) if it reacts with NaHCO${}_3$.

• A. A = HCOOCH${}_3$ B = HOCH${}_2$COOCH${}_3$
• B. A = CH${}_3$COOH B = HCHO
• C. A = HCHO B = CH${}_3$COOH
• D. A = HCHO B = HCOOCH${}_3$

Answer 1

The correct option is D A = HCHO B = HCOOCH${}_3$

Two organic compounds (A) and (B) have same empirical formula $C{H}_{2}O$. Vapour density of (B) is twice the vapour density of (A). Hence, the molecular weight of (A) is twice the molecular weight of (B).
(A) reduces Fehling solution but does not react with $NaHC{O}_3$. Therefore, it is formaldehyde $HCHO$.
Compound (B) neither reacts with $NaHC{O}_3$ nor reduces Fehling solution. Hence, it is not an aldehdye or ketone. It will be methyl formate $HCOOC{H}_3$.