Question

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

• A. V²+ < Cr²+ < Mn²+ < Fe²+ : paramagnetic behaviour
• B. Ni²+ < Co²+ < Fe²+ < Mn²+ : ionic size
• C. Co³+ < Fe³+ < Cr³+ < Sc³+ : stability in aqueous solution
• D. Sc < Ti < Cr < Mn : number of oxidation states

Hint:

Maximum paramagnetism occurs for: d⁵ configuration

Answer 1

The Correct Option is A

Step 1: Paramagnetic behaviour depends on the number of unpaired electrons.
Step 2: Electron configurations: V²+: d³, Cr²+: d⁴, Mn²+: d⁵, Fe²+: d⁶
Step 3: Number of unpaired electrons increases up to d⁵ and then decreases. ⟹ Fe²+ has fewer unpaired electrons than Mn²+ Hence the given order is incorrect.