JEE Chemistry 2026 Question with Solution

Step-by-step solution

Common mistakes

• Mistake: Assuming both reactions release the same gas because both compounds contain an acidic hydrogen. Why it is wrong: Phenol reacts with sodium to give $\mathrm{H_2}$, but carboxylic acids react with bicarbonate to give $\mathrm{CO_2}$. What to do instead: Identify the reagent first, then recall the characteristic gas evolved.

• Mistake: Taking the molar mass of phenol or benzoic acid instead of the gases $x$ and $y$. Why it is wrong: The question asks only for the molar masses of the evolved gases. What to do instead: First determine the identities of $x$ and $y$, then add only their molar masses.

• Mistake: Using $\mathrm{O_2}$ or atomic hydrogen instead of molecular hydrogen for gas $x$. Why it is wrong: Sodium with phenol produces molecular hydrogen, that is $\mathrm{H_2}$, whose molar mass is $2$, not $1$ or $32$. What to do instead: Write the balanced reaction before calculating molar mass.