Board-style MCQs and past-paper questions in the BIEK / Sindh Board pattern. Tap an option to check yourself instantly. Solved questions are at the bottom.
Multiple-choice questions
Solved questions & self-assessment (past papers)
Why is a carboxylic acid more acidic than an alcohol?
When –COOH loses H⁺, the resulting carboxylate ion RCOO⁻ is resonance-stabilised — the negative charge is delocalised equally over both oxygen atoms (two equivalent resonance forms). This lowers its energy, so ionisation is favoured. An alkoxide RO⁻ from an alcohol has no such resonance, so alcohols are barely acidic.
Explain the esterification of CH₃COOH with C₂H₅OH (and the role of conc. H₂SO₄).
CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O. Conc. H₂SO₄ catalyses the reaction (protonates the carbonyl so the alcohol can attack) and acts as a dehydrating agent, removing water to shift the equilibrium toward more ester (Le Chatelier). The –OH leaves from the acid and the –H from the alcohol, joining to form water.
Arrange acyl chloride, ester, amide and anhydride in order of reactivity, with reason.
acyl chloride > anhydride > ester > amide. Reactivity depends on the leaving group and how stabilised the carbonyl is: Cl⁻ is the best leaving group (acyl chloride most reactive), while in an amide the nitrogen lone pair feeds into the carbonyl and –NH₂ is a poor leaving group (least reactive).