Assertion (A): Magnetic moment of `Ni^(+2)` ions can be very close to that of `Ti^(+2)` ions
Reason (R): Both metal ions have equal no. of unpaired electrons

Options

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true and R is not the correct explanation of A
C. A is true but Ris false
D. A is false but R is true

Answer

To solve the given question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step 1: Understanding the Assertion (A)

The assertion states that the magnetic moment of Ni²⁺ ions can be very close to that of Ti²⁺ ions.

### Step 2: Determine the Electronic Configuration

- **Nickel (Ni)** has an atomic number of 28. Its electronic configuration is:
\[ \text{Ni: } [Ar] 3d^8 4s^2 \]
When it loses 2 electrons to form Ni²⁺, the configuration becomes:
\[ \text{Ni}^{2+}: [Ar] 3d^8 4s^0 \]

- **Titanium (Ti)** has an atomic number of 22. Its electronic configuration is:
\[ \text{Ti: } [Ar] 3d^2 4s^2 \]
When it loses 2 electrons to form Ti²⁺, the configuration becomes:
\[ \text{Ti}^{2+}: [Ar] 3d^2 4s^0 \]

### Step 3: Count the Unpaired Electrons

- For **Ni²⁺** with the configuration \(3d^8\):
- The 3d subshell can hold a maximum of 10 electrons. In the case of \(3d^8\), there are 2 unpaired electrons.

- For **Ti²⁺** with the configuration \(3d^2\):
- The 3d subshell has 2 unpaired electrons.

### Step 4: Calculate the Magnetic Moment

The magnetic moment (\(\mu\)) can be calculated using the formula:
\[ \mu = \sqrt{n(n + 2)} \text{ Bohr magnetons} \]
where \(n\) is the number of unpaired electrons.

- For **Ni²⁺**:
\[ n = 2 \Rightarrow \mu_{Ni^{2+}} = \sqrt{2(2 + 2)} = \sqrt{8} \approx 2.83 \text{ Bohr magnetons} \]

- For **Ti²⁺**:
\[ n = 2 \Rightarrow \mu_{Ti^{2+}} = \sqrt{2(2 + 2)} = \sqrt{8} \approx 2.83 \text{ Bohr magnetons} \]

### Step 5: Conclusion

Since both Ni²⁺ and Ti²⁺ have the same number of unpaired electrons (2), their magnetic moments are indeed very close to each other.

- **Assertion (A)** is correct.
- **Reason (R)** is also correct, as both metal ions have equal numbers of unpaired electrons.

### Final Answer

Both the assertion and the reason are correct, and the reason is the correct explanation of the assertion.

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