Which of the following reagents can be employed to successfully distinguish a terminal alkyne (like — Hydrocarbons Chemistry Question

💡 Solution & Explanation

(A) Tollens' reagent reacts with the acidic hydrogen of terminal alkynes to form a white precipitate of silver acetylide. (B) Ammoniacal cuprous chloride forms a distinct red precipitate of copper acetylide with terminal alkynes. Both are standard visual tests. While Na metal reacts with terminal alkynes to release $H_2$ gas, it's less standard for a 'visible chemical change/precipitate test' in routine qualitative differentiation compared to A and B. Bromine water (D) tests for general unsaturation and will decolorize for both 1-butyne and 2-butyne.