The correct order of acidic strength of the major products formed in the given reactions, is : A. B. CH ₃ CH ₂ CHO [ ] [ Ag ( NH ₃ )₂ ]⁺, OH ⁻ [ B ] C. CH ₄+ O ₂ [ (ii) Na ₂ Cr ₂ O ₇ / H ⁺] (i) [ C ] D. PhCH ₂ MgBr + CO ₂ [ H ₃ O ⁺] Dry ether [ D ] Choose the correct answer from the options given below :

Step-by-step solution

Product [A]: From PhNH₂, steps (1) NaNO₂ + HCl forms diazonium salt, (2) CuCN gives benzonitrile, (3) H₃O⁺/Δ hydrolyzes to benzoic acid (PhCOOH), pKa ≈ 4.2. Product [B]: From CH₃CH₂CHO, Tollens' oxidation with [Ag(NH₃)₂]^+ produces acetic acid (CH₃COOH), pKa ≈ 4.8. Product [C]: From CH₄ + O₂ with heat and Na₂Cr₂O₇/H⁺ produces formic acid (HCOOH), pKa ≈ 3.8 (strongest acid). Product [D]: From PhCH₂MgBr + CO₂, the Grignard reaction produces phenylacetic acid (PhCH₂COOH), pKa ≈ 4.3. Acidic strength order (lower pKa =