Select correct answers from the choices A, B, C, D which are given. Write down only the letter corresponding to the correct answer.
The hydroxide of which cation is not formed on adding ammonium hydroxide in its solution? `Zn^(2+)`, `Ca^(2+)`, `Cu^(2+)`, `Fe^(3+)`

Options

A. `Zn^(2+)`
B. `Ca^(2+)`
C. `Cu^(2+)`
D. `Fe^(3+)`

Answer

To solve the question, we need to analyze the behavior of each cation when ammonium hydroxide (NH4OH) is added to their solutions.

1. **Zinc Ion (Zn²⁺)**: When ammonium hydroxide is added to a solution containing zinc ions, zinc hydroxide (Zn(OH)₂) is formed as a precipitate. This indicates that zinc hydroxide is indeed formed.

2. **Calcium Ion (Ca²⁺)**: When ammonium hydroxide is added to a solution containing calcium ions, no reaction occurs. Calcium hydroxide (Ca(OH)₂) is not formed because ammonium hydroxide is a weak base and cannot displace the anion associated with calcium salts. Therefore, calcium hydroxide is not formed.

3. **Copper Ion (Cu²⁺)**: When ammonium hydroxide is added to a solution containing copper ions, copper hydroxide (Cu(OH)₂) is formed as a precipitate. This indicates that copper hydroxide is formed.

4. **Iron Ion (Fe³⁺)**: When ammonium hydroxide is added to a solution containing iron ions, iron hydroxide (Fe(OH)₃) is formed as a precipitate. This indicates that iron hydroxide is formed.

Based on this analysis, the only cation for which the hydroxide is not formed upon the addition of ammonium hydroxide is **Calcium (Ca²⁺)**.

Thus, the correct answer is:
**B**