Which of the following pairs is coloured in aqueous solution?

Options

A. `Sc^(3+), Co^(2+)`
B. `Ni^(2+),Cu^(+)`
C. `Ni^(2+), Ti^(3+)`
D. `Sc^(3+),Ti^(3+)`

Answer

C

Explanation

`._(28)Ni = 2 s^(2) 2s^(2) 2p^(6) 3 s^(2) 3 p^(6) 3 d^(8) 4 s^(2)`
`Ni^(2+) = 1s^(2) 2s^(2) 2P^(6) 3s^(2) 3P^(6) 3 d^(8)`

`._(22)Ti = 1 s^(2) 2 s^(2) 2 p^(6) 3 s^(2) 3 p^(6) 3 d^(2) 4 s^(2)`
`Ti^(3+) = 1 s^(2) 2 s^(2) 2p^(6) 3 s^(2) 3 p^(6) 3 d^(1)`
Hence, `Ni^(2+)` and `Ti^(3+)` are coloured in aqueous solution due to the presence of upaired electrons in d-subshell.