Question

Which of the following arrangements does not represent the correct order of the property stated against it?

• A. \( \text{V}^{2+}<\text{Cr}^{2+}<\text{Mn}^{2+}<\text{Fe}^{2+} \): Paramagnetic behaviour
• B. \( \text{Ni}^{2+}<\text{Co}^{2+}<\text{Fe}^{2+}<\text{Mn}^{2+} \): Ionic size
• C. \( \text{Co}^{3+}<\text{Fe}^{3+}<\text{Cr}^{3+}<\text{Sc}^{3+} \): Stability in aqueous solution
• D. \( \text{Sc}<\text{Ti}<\text{Cr}<\text{Mn} \): Number of oxidation states

Hint:

The paramagnetic behavior of an ion is directly linked to the number of unpaired electrons. More unpaired electrons lead to a stronger paramagnetic behavior.

Answer 1

The Correct Option is A

The number of unpaired electrons in an ion's electronic configuration dictates its paramagnetic behavior. The configurations and their corresponding unpaired electrons are: \( \text{V}^{2+}: 3d^3 \) (3 unpaired electrons), \( \text{Cr}^{2+}: 3d^4 \) (4 unpaired electrons), \( \text{Mn}^{2+}: 3d^5 \) (5 unpaired electrons), and \( \text{Fe}^{2+}: 3d^6 \) (4 unpaired electrons). Consequently, the correct order of paramagnetic behavior, based on the number of unpaired electrons, is \( \text{V}^{2+}<\text{Cr}^{2+}<\text{Fe}^{2+}<\text{Mn}^{2+}. \) Therefore, Option (1) does not accurately represent this order.

Final Answer: \[ \boxed{\text{V}^{2+}<\text{Cr}^{2+}<\text{Mn}^{2+}<\text{Fe}^{2+}}. \]