Question 8

**Analysis of the sequence** Starting compound: a six‑membered lactone (tetrahydropyran‑2‑one) bearing a benzyl group at C‑4 (β to the carbonyl). - **P (LiAlH₄):** The lactone is reduced to a diol: HOCH₂CH₂–CH(CH₂Ph)–CH₂CH₂OH. The former stereocentre now carries two identical –CH₂CH₂OH arms, so P is **achiral** → optically inactive. (A) is false. - **Q (CrO₃–H₂SO₄, Jones oxidation):** Both primary alcohols are oxidised to –COOH: HOOC–CH₂–CH(CH₂Ph)–CH₂–COOH, a dicarboxylic acid → gives CO₂ effervescence with aqueous NaHCO₃. (C) is true. - **R (NaOH + CaO, Δ, soda‑lime decarboxylation):** Both –COOH groups are lost → CH₃–CH(CH₂Ph)–CH₃ (isobutylbenzene), an alkane, not an alkyne. (D) is false. - **S (conc. H₂SO₄, 443 K):** Dehydration of the diol gives an alkene (diene) which decolourises cold alkaline KMnO₄ → positive Baeyer’s test. (B) is true. **Correct statements: (B) and (C).**