A compound C5H10O gives an orange precipitate with 2,4-DNP, does not reduce Tollens' reagent and gives no yellow precipitate with $I X_{2}$ / $NaOH$ . It is treated with $CH X_{3} MgBr$ and then $H X_{3} O X^{+}$ to give Y. Y is

Answer: A

The first test shows a carbonyl group, Tollens shows it is a ketone and iodoform shows no methyl ketone, so it is

CH X_{3} CH X_{2} COCH X_{2} CH X_{3}

(pentan-3-one). Methyl Grignard addition gives the tertiary alcohol

(C X_{2} H X_{5}) X_{2} C (OH) CH X_{3}