Assertion`Cu^(o+)` ion is unstable in aqueous solution, whereas `Fe^(2+)` ion is stable
`Cu^(o+)` disproportionate in aqueous solution .

Options

A. If both `(A)` and ` (R )` are correct and `(R )` is the correct explanation of `(A ) ` .
B. If both `(A)` and ` (R )` are correct and `(R )` is the correct explanation of `(A ) ` .
C. If`(A)` is correct, but `( R )` is incorrect .
D. Both `(A)` and `(R ) ` are incorrect .

Answer

To solve the question, we need to analyze the assertion and reason provided regarding the stability of the ions \( \text{Cu}^+ \) and \( \text{Fe}^{2+} \) in aqueous solution.

### Step 1: Understand the Electronic Configuration
- **Copper (Cu)** has an atomic number of 29, and its electronic configuration is \( [Ar] 3d^{10} 4s^1 \).
- When copper loses one electron to form \( \text{Cu}^+ \), its configuration becomes \( [Ar] 3d^{10} 4s^0 \).
- **Iron (Fe)** has an atomic number of 26, and its electronic configuration is \( [Ar] 3d^6 4s^2 \).
- When iron loses two electrons to form \( \text{Fe}^{2+} \), its configuration becomes \( [Ar] 3d^6 4s^0 \).

### Step 2: Analyze Stability in Aqueous Solution
- The \( \text{Cu}^+ \) ion is known to be unstable in aqueous solutions. It tends to undergo disproportionation, which is a reaction where a single species is both oxidized and reduced.
- The disproportionation of \( \text{Cu}^+ \) can be represented as:
\[ 2 \text{Cu}^+ \rightarrow \text{Cu}^0 + \text{Cu}^{2+} \]
In this reaction, one \( \text{Cu}^+ \) ion is reduced to elemental copper (\( \text{Cu}^0 \)), while another \( \text{Cu}^+ \) ion is oxidized to \( \text{Cu}^{2+} \).

### Step 3: Compare with \( \text{Fe}^{2+} \)
- In contrast, the \( \text{Fe}^{2+} \) ion is stable in aqueous solution and does not undergo disproportionation. It remains as \( \text{Fe}^{2+} \) without converting to other oxidation states in solution.

### Step 4: Conclusion
- The assertion states that \( \text{Cu}^+ \) is unstable in aqueous solution, while \( \text{Fe}^{2+} \) is stable. This is true.
- The reason given is that \( \text{Cu}^+ \) undergoes disproportionation in aqueous solution, which is also true.
- Therefore, both the assertion and reason are correct, and the reason correctly explains the assertion.

### Final Answer
The answer is option A: Both the assertion and reason are correct, and the reason is the correct explanation of the assertion.

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