Question

Which actinoid from following has smallest ionic size in \(+3\) state?

• A. Pa
• B. Cm
• C. Fm
• D. Lr

Hint:

Actinoid contraction: ionic size falls steadily across the series.

Answer 1

The Correct Option is D

Step 1: Trend:
Ionic radius of $M^{3+}$ decreases from Ac to Lr.

Step 2: Choose:
Among the choices Lr has the largest atomic number ($103$), so it sits at the end of the series and has the smallest radius.

Final Answer:
The smallest ion is $\text{Lr}^{3+}$, option (D). \[ \boxed{\text{Lr}} \]