Q. Which of the following ions is the strongest oxidizing agent? (Atomic Number of Ce = 58, Eu = 63, Tb = 65, Lu = 71)
A) $\text{Eu}^{2+}$
B) $\text{Tb}^{4+}$
C) $\text{Lu}^{3+}$
D) $\text{Ce}^{3+}$
Explanation
[Solution by Dr. Abubacker] $\text{Eu}^{2+}$ is a reducing agent (it tends to become $\text{Eu}^{3+}$); $\text{Lu}^{3+}$ ($4f^{14}$) and $\text{Ce}^{3+}$ are stable and not oxidising. $\text{Tb}^{4+}$ readily gains an electron to form $\text{Tb}^{3+}$ and is the strongest oxidant. (Medium confidence: answer follows the official key.) Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.