Question

Ammonia forms the complex ion $[Cu(NH_3)_4]^{2+}$ with copper ions in alkaline solution but not in acidic solution. The probable reason for this is

• A. In acidic solution hydration protects $Cu^{2+}$ ion
• B. In acidic solution proton coordinates withammonia molecules to form $NH^+_4$ ions and $NH_3$ molecules are not available
• C. In alkaline solutions insoluble $Cu(OH)_2$ is precipirated which is soluble in excess of any alkali
• D. Copper hydroxide is amphoteric substance

Answer 1

Answer: (B)

In acidic solution proton coordinates with ammonia molecules to form $NH^+_4$ ions and $NH_3$ molecules are not available for complex formation