Chemistry Question on d -and f -Block Elements

Question

The aqueous solution containing which one of the following ions will be colourless?(Atomic no: Sc=21, Fe=26, Ti=22, Mn=25)

Answer 1

(a) $_{21}Sc^{3+}$ = 1s2, 2s2, 2p6, 3s2, 3p6
Because there are no unpaired electrons in the d-subshell, it is colourless.

(b) $_{26}Fe^{2+}$ = 1s2, 2p6, 3s2, and 3d6
The presence of four unpaired electrons in the d-subshell is what gives it its hue.

(c) $_{22}Ti^{3+}$ =1s2,2s2, 2p6, 3s2, and 3p6
Because there is one unpaired electron in the d-subshell, it is coloured.

(d) $_{25}Mn^{2+}$ = 1s2, 2s2, 2p6, 3s2, and 3p6 3d5.
It has colour because the d-subshell contains five unpaired electrons.

Therefore, the correct option is (A): Sc3+