The aqueous solution containing which one of the following ions will be colourless
(Atomic number `Sc = 21, Fe = 26, Ri = 22, Mn = 25)`

Options

A. `Ti^(3+)`
B. `Mn^(2+)`
C. `Sc^(3+)`
D. `Fe^(2+)`

Answer

C

Explanation

`._(21)Sc = 1 s^(2) 2 s^(2) 2 P^(6) 3 s^(2) 3 p^(6) 3 d^(1) 4 s^(2)`
So, `Sc^(3+) = 1s^(2) 2s^(2) 2p^(6) 3 s^(2) 3 P^(6)`
It is colourless due to the absence of unparied electrons in the d-subshell.