Ammonia form the complex ion`[Cu(NH_(3))_(4)]^(2+)` with copper ions in the alkaline solution but not In acidic solution.What is the statement-2 for it?

Options

A. In acidic solution hydration protect copper ions
B. In acidic solution protons co-ordinate with ammonia molecules forming `NH_(4)^(+)` ion and `NH_(3)` molecules are not available
C. In alkaline solution insolution `Cu(OH)_(2)` is precipitated which is soluble in excess of any alkali
D. Copper hydroxide is an amphoteric substance.

Explanation

To answer the question regarding why ammonia forms the complex ion \([Cu(NH_3)_4]^{2+}\) in alkaline solutions but not in acidic solutions, we can break down the explanation into a step-by-step solution.

### Step-by-Step Solution:

1. **Understanding the Formation of Complex Ion**:
- In alkaline solutions, ammonia (\(NH_3\)) acts as a ligand and can coordinate with copper ions (\(Cu^{2+}\)) to form the complex ion \([Cu(NH_3)_4]^{2+}\). This occurs because ammonia has a lone pair of electrons on the nitrogen atom that can be donated to the copper ion.

2. **Behavior of Ammonia in Acidic Solutions**:
- In acidic solutions, ammonia reacts with protons (\(H^+\)) to form ammonium ions (\(NH_4^+\)). The reaction can be represented as:
\[ NH_3 + H^+ \rightarrow NH_4^+ \]
- This reaction effectively removes ammonia from the solution, converting it into ammonium ions.

3. **Lack of Lone Pair in Ammonium Ion**:
- The ammonium ion (\(NH_4^+\)) does not have a lone pair of electrons available for donation. This is crucial because ligands must have available lone pairs to form coordinate bonds with metal ions.

4. **Conclusion**:
- Since \(NH_4^+\) cannot act as a ligand due to the absence of a lone pair, it cannot coordinate with copper ions to form the complex \([Cu(NH_3)_4]^{2+}\). Hence, the formation of the complex ion is inhibited in acidic solutions.

### Statement 2:
- The statement that can be derived from the above reasoning is: "In acidic solution, protons coordinate with ammonia molecules forming \(NH_4^+\) ions, and \(NH_3\) molecules are not available to form complexes."