Question

Which one of the following forms a colourless solution in aqueous medium ?
(Atomic number : `Sc =21, Ti = 22, V = 23`, and `Cr = 24`)
A. `V^(3+)`
B. `Cr^(3+)`
C. `Ti^(3+)`
D. `Sc^(3+)`

Answer 1

Correct Answer - D
The electronic configuration of Sc is
`1s^(2),2s^(2)2p^(6),3s^(2)3p^(6)3d^(1),4s^(2)`
and configuration of `Sc^(3+)` is
`1s^(2),2s^(2)2p^(6), 3s^(2)3p^(6)`
So, `Sc^(3+)` is colourless due to absence of electrons in d-orbital.