The reason for the stability of the $Gd^{3+}$ ion is.....

Which of the following metal ions is diamagnetic?

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.

The correct set of ions (aqueous solution) with the same colour from the following is:

Which of the following pairs of ions are both colored in aqueous solution? (Atomic numbers: $Sc = 21, Ti = 22, Co = 27, Ni = 28, Cu = 29$)

Determine whether the following statements are True $(T)$ or False $(F)$:
$(a)$ The atomic radii of the elements of the second transition series $(4d)$ are larger than those of the first transition series $(3d)$.
$(b)$ $Cr^{+}$,$Mn^{2+}$,and $Fe^{3+}$ have the same electronic configuration.
$(c)$ $Cr^{+}$,$Mn^{2+}$,and $Fe^{3+}$ have the same $d^5$ electronic configuration.