The ions from among the following which are colourless are:

Options

A. (i) and (ii) only
B. (i),(ii) and (iii)
C. (iii) and (iv)
D. (ii) and (iii)

Answer

A

Explanation

(i) Valence shell electron configuration of `Ti^(4+)` is `3d^(0) 4 s^(0)`. As there is no unparied electrons for d-d trastition, the solution of ions will be colourless
(ii) Valence shell electron configuration of `Cu^(+)` is `3 d^(10) 4 s^(0)`. As all electons are unparied, there is no d-d trasition, so the solution of ions will be colourless.
(iii) Valence shell electron configuration of `Co^(3 +)` is `3 d^(6) 4s^(0)`. As there are 4 upaired electrons, there is d-d transition of electron, so the solution of ions will be coloured.
(iv) Valenec shell electron configuration of `Fe^(2 +)` is `3 d^(6) 4 s^(0)`. As there are 4 upaired electrons. there is d-d transition of electron, so the solution of ions will be coloured.