Which is the most acidic compound among the following?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Ethanol
Each alkyl group on the carbon carrying –OH is electron-releasing and lowers the acid strength, so the fewer the alkyl groups, the stronger the acid.
Ethanol, \( \ce{CH3CH2OH} \) — a primary alcohol: one alkyl group on the –OH carbon; the most acidic of the three.
Propan-2-ol, \( \ce{(CH3)2CHOH} \) — a secondary alcohol: two alkyl groups; less acidic.
2-Methylpropan-2-ol, \( \ce{(CH3)3COH} \) — a tertiary alcohol: three alkyl groups; the least acidic.
The three differ in the number of alkyl groups, so they cannot have the same acidity.
NCERT (2026-27 edition):
7.4.4 Chemical Reactions
