In the $3d$ series of the $d$-block elements,which element has the maximum atomic size?

Explain giving reasons:
$(i)$ Transition metals and many of their compounds show paramagnetic behaviour.
$(ii)$ The enthalpies of atomisation of the transition metals are high.
$(iii)$ The transition metals generally form coloured compounds.
$(iv)$ Transition metals and their many compounds act as good catalysts.

Find the species having the magnetic moment value of $5.92 \ BM$.

The electronic structure $(n - 1)d^{1 - 10}ns^{0 - 2}$ is characteristic of

The element with the highest standard reduction potential (in volt) for the process $M^{2+} \rightarrow M$ among the first row of transition elements is:

Ionisation enthalpies of $Ce$,$Pr$ and $Nd$ are higher than $Th$,$Pa$ and $U$. Why?