Question
Chemistry Question on d -and f -Block Elements
In which of the following pairs are both the ions coloured in aqueous solution? (Atomic number: Sc = 21, Ti = 22, Ni = 28, Cu = 29, Co = 27)
A
Ni2+, Ti3+
B
Sc3+, Ti3+
C
Sc3+, Co2+
D
Ni2+, Cu+
Answer
Ni2+, Ti3+
Explanation
Solution
28Ni = 1s2 2s2 2p6 3s2 3p6 3d8 4s2
Ni2+=1s2 2s2 2p6 3s2 3p6 3d8
22Ti = 1s2 2s2 2p6 3s2 3p6 3d2 4s2
Ti3+=1s2 2s2 2p6 3s2 3p6 3d1
Ni2+ and Ti3+ ions are coloured ions in aqueous solution due to the presence of unpaired electrons d − subshell.
So, the correct option is (A): Ni2+, Ti3+