See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

The question asks which reagent(s) can convert chloromethane (CH3Cl) to methane (CH4), i.e., replace the C–Cl bond with a C–H bond (dehalogenation/reduction). Step 1 – Concept: We need a reagent that removes the chlorine from CH3Cl and replaces it with hydrogen, effectively reducing the carbon–halogen bond. Step 2 – Option (a) Zn / H+: Zinc metal in the presence of a proton source (H+) acts as a reducing agent. Zn reduces alkyl halides; the zinc inserts into the C–Cl bond and the proton source provides H, giving CH4. This is a valid reductive dehalogenation pathway. Step 3 – Option (b) LiAlH4: Lithium aluminium hydride is a strong hydride-delivery reagent. It delivers H⁻ to the carbon bearing the halide in an SN2-type fashion, replacing Cl with H. CH3Cl + LiAlH4 → CH4. This is a well-known reduction of alkyl halides. Step 4 – Option (c) Mg / (ether) then H2O: CH3Cl reacts with Mg in dry ether to form the Grignard reagent CH3MgCl. Upon treatment with a proton source (H2O), the Grignard reagent is protonated: CH3MgCl + H2O → CH4 + Mg(OH)Cl. This cleanly gives methane. Step 5 – Conclusion: All three methods independently accomplish the conversion CH3Cl → CH4. Therefore, option (d) all of these is correct. Therefore, the correct answer is D.