A red precipitate of copper (I) carbide is formed when ammonium solution of copper (I) chloride is introduced into

A red precipitate of copper (I) carbide is formed when ammonium solution of copper (I) chloride is introduced into 

A. CH2=CH-CH2-CH3

B. CH3-CH2-C三CH

C. CH3-CH2-CH2-CH3

D. CH3-C三C-CH3

The red precipitate of copper(I) carbide (copper acetylide) is formed only with terminal alkynes (alkynes that have a ≡C–H bond).

Let’s check the options:

• A. CH₂=CH–CH₂–CH₃ → Alkene ❌

• B. CH₃–CH₂–C≡CH → Terminal alkyne (has ≡C–H) ✅

• C. CH₃–CH₂–CH₂–CH₃ → Alkane ❌

• D. CH₃–C≡C–CH₃ → Internal alkyne (no ≡C–H) ❌

🔑 Key rule:
Ammoniacal Cu(I) chloride reacts with terminal alkynes to form a red precipitate of copper(I) carbide.

✅ Correct answer: B. CH₃–CH₂–C≡CH

PQN: 35