question_answer

Ammonia forms the complex ion \[{{[Cu{{(N{{H}_{3}})}_{4}}]}^{2+}}\] with copper ions in the alkaline solutions but not in acidic solutions. What is the reason for it?     AIEEE  Solved  Paper-2003

A) In acidic solutions hydration protects copper ions

B) In acidic solutions protons coordinate with ammonia molecules forming \[NH_{4}^{+}\] ions and \[N{{H}_{3}}\] molecules are not available

C) In alkaline solutions insoluble \[Cu{{(OH)}_{2}}\] is precipitated which is soluble in excess of any alkali

D) Copper hydroxide is an amphoteric substance