Question

The transition metal ion with the least ionic radius (in pm) is

• A. \(Sc^{3+}\)
• B. \(Ti^{3+}\)
• C. \(V^{3+}\)
• D. \(Cr^{3+}\)
• E. \(Mn^{3+}\)

Hint:

For same oxidation state, ionic radius decreases across the period due to increasing nuclear charge.

Answer 1

The Correct Option is D

Concept: Across a period, ionic radius decreases due to increase in effective nuclear charge.

Step 1: Compare ions across 3d series.

• All ions have same charge (+3)
• Increasing atomic number $\rightarrow$ stronger nuclear attraction

Step 2: Trend in ionic radius.
\[ Sc^{3+}>Ti^{3+}>V^{3+}>Cr^{3+}<Mn^{3+} \] Cr\(^{3+}\) has smallest radius due to maximum effective nuclear charge before slight increase.