Assertion (A): Ethanol is a weaker acid than phenol.
Reason (R): Sodium ethoxide can be prepared by the reaction of ethanol with aqueous NaOH.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) is true but (R) is false.
An acid gives up a proton; the more stable the anion left behind, the stronger the acid.
Assertion (A): Ethanol is a weaker acid than phenol. — True. Phenol reacts with aqueous sodium hydroxide to form sodium phenoxide, which ethanol does not do:
\( \displaystyle \ce{C6H5OH + NaOH -> C6H5ONa + H2O} \)
In the phenoxide ion the negative charge is delocalised over the ring, while in the ethoxide ion it stays localised on oxygen, so phenol ionises more readily.
Reason (R): Sodium ethoxide can be prepared by the reaction of ethanol with aqueous NaOH. — False. Water is a stronger acid than ethanol, and sodium ethoxide is a stronger base than sodium hydroxide. So in water the ethoxide ion takes a proton back from water:
\( \displaystyle \ce{C2H5ONa + H2O -> C2H5OH + NaOH} \)
Ethanol and aqueous NaOH therefore give no sodium ethoxide. It is made by the reaction of ethanol with sodium metal:
\( \displaystyle \ce{2C2H5OH + 2Na -> 2C2H5ONa + H2} \)
NCERT (2026-27 edition):
(iii) Acidity of phenols – “The reaction of phenol with aqueous sodium hydroxide indicates that phenols are stronger acids than alcohols and water.”
(ii) Acidity of alcohols – “Alcohols are, however, weaker acids than water. … we note that an alkoxide ion is a better proton acceptor than hydroxide ion, which suggests that alkoxides are stronger bases (sodium ethoxide is a stronger base than sodium hydroxide).”