Question

When $C_{2}H_{2}, CH_{4}$ and $C_{2}H_{4}$ pass through a test tube which have ammoniacal $Cu_{2}Cl_{2}$, find out which gas comes out unaffected from test tube?

• A. $C_{2}H_{2}$ and $CH_{4}$
• B. $C_{2}H_{2}$ and $C_{2}H_{4}$
• C. $C_{2}H_{4}$ and $CH_{4}$
• D. $C_{2}H_{2}$

Answer 1

Answer: (C)

Alkynes, containing terminal $H$-atom, reacts with ammoniacal $Cu_{2}Cl_{2}$ solution. So, $C_{2}H_{2}$ reacts with ammoniacal $Cu_{2}Cl_{2}$ solution while $CH_{4}$ and $C_{2}H_{4}$ remain unaffected
$HC \equiv CH \ce{ ->[{\text{Ammoniacal}}][{Cu_{2}Cl_{2}}] }CuC\equiv CCu $