Question

Which of the following exhibits only $+3$ oxidation state?

• A. $Th$
• B. $Ac$
• C. $Pa$
• D. $U$

Answer 1

Answer: (B)

$Ac$

The atomic number of $Ac$ is 89.

Electronic configuration $=\left[Rn\right]6d^{1}7s^2$

The stable oxidation state $\Rightarrow +3$

$Th=+3,+4$

$Pa=+3,+4,+5$

$U=+3,+4,+5,+6$

Hence, option $B$ is correct.