Question

Pair of transition metal ions having the same number of unpaired electrons is :

• A. $\mathrm{V}^{2+}, \mathrm{Co}^{2+}$
• B. $\mathrm{Ti}^{2+}, \mathrm{Co}^{2+}$
• C. $\mathrm{Fe}^{3+}, \mathrm{Cr}^{2+}$
• D. $\mathrm{Ti}^{3+}, \mathrm{Mn}^{2+}$

Hint:

The number of unpaired electrons in transition metal ions depends on their electronic configuration.

Answer 1

The Correct Option is A

1. $\mathrm{V}^{2+}$: - $\mathrm{V}^{2+} \Rightarrow 3 \mathrm{~d}^{3} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 3
2. $\mathrm{Co}^{2+}$: - $\mathrm{Co}^{2+} \Rightarrow 3 \mathrm{~d}^{7} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 3
3. $\mathrm{Ti}^{2+}$: - $\mathrm{Ti}^{2+} \Rightarrow 3 \mathrm{~d}^{2} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 2
4. $\mathrm{Fe}^{3+}$: - $\mathrm{Fe}^{3+} \Rightarrow 3 \mathrm{~d}^{5} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 5 5. $\mathrm{Cr}^{2+}$: - $\mathrm{Cr}^{2+} \Rightarrow 3 \mathrm{~d}^{4} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 4 6. $\mathrm{Ti}^{3+}$: - $\mathrm{Ti}^{3+} \Rightarrow 3 \mathrm{~d}^{1} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 1 7. $\mathrm{Mn}^{2+}$: - $\mathrm{Mn}^{2+} \Rightarrow 3 \mathrm{~d}^{5} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 5 Therefore, the correct answer is (1) $\mathrm{V}^{2+}, \mathrm{Co}^{2+}$.