Identify the pair in which both elements typically exhibit only one oxidation state.

Which of the following is responsible for the stability of $Ce^{4+}$?

Of the following outer electronic configurations of atoms,which one achieves the highest oxidation state?

Determine whether the following statements are True $(T)$ or False $(F)$:
$(a)$ An element or its ion that does not have a completely filled $d$-orbital is considered a transition element.
$(b)$ $Sc$ is a transition element.
$(c)$ $Zn$ is a transition element.
$(d)$ The energy difference between $(n-1)d$ and $ns$ orbitals is high.

Which of the following transition metals is considered the softest?

Higher second ionisation enthalpies than expected are observed for