Which of the following compounds reacts with acids to give salts?

The correct answer is Option (3) → Amines

Amines have an unshared pair of electrons on nitrogen, so they act as Lewis bases. Being basic, they react with acids to form salts (substituted ammonium salts), just as ammonia gives ammonium chloride:

    \( \displaystyle \ce{R-NH2 + HCl -> R-NH3+Cl-} \)

    \( \displaystyle \ce{C6H5NH2 + HCl -> C6H5NH3+Cl-} \)

So the compounds that react with acids to give salts are amines.

Why the other options are incorrect

• Option (1) Ethers — Incorrect. The ether oxygen is only a very weak base: ethers are protonated by strong acids, but with HX they are cleaved (\( \ce{R-O-R + HX -> R-OH + R-X} \)) rather than forming stable salts.

• Option (2) Phenols — Incorrect. Phenols are weak acids; they form salts with bases, e.g. \( \ce{C6H5OH + NaOH -> C6H5O^-Na+ + H2O} \), not with acids.

• Option (4) Carbonyl Compound — Incorrect. Aldehydes and ketones are neutral; they typically undergo nucleophilic addition at the C=O group.

NCERT (2026-27 edition):
Basic Character of Amines – “Amines, being basic in nature, react with acids to form salts. … Amine salts on treatment with a base like NaOH, regenerate the parent amine. Amine salts are soluble in water but insoluble in organic solvents like ether. This reaction is the basis for the separation of amines from the non basic organic compounds insoluble in water. The reaction of amines with mineral acids to form ammonium salts shows that these are basic in nature. Amines have an unshared pair of electrons on nitrogen atom due to which they behave as Lewis base.”