See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Step 1: Identify product (A). Calcium carbide (CaC2) reacts with water (H2O) in a hydrolysis reaction to produce acetylene (ethyne, HC≡CH) and calcium hydroxide. So A = Acetylene (HC≡CH). Step 2: Identify product (B). When acetylene is passed over a red hot copper tube (or red hot iron/copper catalyst at high temperature), it undergoes trimerization — three molecules of acetylene combine to form benzene (C6H6). This is the classic cyclic trimerization of acetylene. 3 HC≡CH → C6H6 (Benzene) Step 3: Evaluate options. (a) Toluene (C6H5CH3) — would require a methyl group source, not formed here. (b) Ethyl-benzene (C6H5C2H5) — requires additional carbon source, not formed here. (c) Benzene (C6H6) — correctly formed by trimerization of acetylene over red hot Cu tube. (d) Butyne — a C4 alkyne, not the product of acetylene trimerization. The trimerization of acetylene over a red hot copper tube is a well-known reaction producing benzene. Therefore, the correct answer is C.