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 paramagnetic behavior of an ion is governed by the number of unpaired electrons in its electronic configuration.
The configurations are as follows:
\( \text{V}^{2+}: 3d^3 \) (3 unpaired electrons),
\( \text{Cr}^{2+}: 3d^4 \) (4 unpaired electrons),
\( \text{Mn}^{2+}: 3d^5 \) (5 unpaired electrons),
\( \text{Fe}^{2+}: 3d^6 \) (4 unpaired electrons).
Based on the number of unpaired electrons, the correct order of paramagnetic behavior is:
\[ \text{V}^{2+}<\text{Cr}^{2+}<\text{Fe}^{2+}<\text{Mn}^{2+}. \] Thus, the arrangement presented in Option (1) does not reflect the correct order of paramagnetic behavior. 

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