Which of the following elements in their respective oxidation states develops the highest spin-only magnetic moment?

Match the following atoms/ions with their correct electronic configurations:

Atom/Ion	Electronic Configuration
$(1) \ Cu$	$(A) 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^{10}$
$(2) \ Cu^{2+}$	$(B) 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^{10}, 4s^2$
$(3) \ Zn^{2+}$	$(C) 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^{10}, 4s^1$
$(4) \ Cr^{3+}$	$(D) 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^9$
	$(E) 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^3$

Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following points:
$(i)$ electronic configurations,
$(ii)$ oxidation states,
$(iii)$ ionisation enthalpies,and
$(iv)$ atomic sizes.

Which one of the following characteristics of the transition metals is associated with their catalytic activity?

The chloride of which of the following elements is coloured?

Assertion : Cuprous ion $(Cu^+)$ has unpaired electrons while cupric ion $(Cu^{2+})$ does not.
Reason : Cuprous ion $(Cu^+)$ is colourless whereas cupric ion $(Cu^{2+})$ is blue in the aqueous solution.