The ions from among the following which are colourless are `:`
`(i)Ti^(+4)" "(ii)Cu^(+1)" "(iii)Co^(+3)" "(iv)Fe^(+2)`

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^(10)4s^(0)`. As theere is no unpaired electrons for d-d transition, the solution of ions will be colourless.
(ii) Valence shell electron configuration of `Cu^(+)` is `3d^(10)4s^(0)`. As all electrons are paired, there is no d-d transiton, so the solution of ions will be colourless.
(iii) Valence shell electron configuraiton of `Co^(3+)` is `3d^(6)4s^(0)`. As there are 4 unpaired electrons, there is d-d transition of electron, so the solution of ions will be coloured.
(iv) Valence shell electron configuration of `Fe^(2+)` is `3d^(6)4s^(0)`. As there are 4 unpaired electrons, there is d-d transition of electron, so the solution of ions will be coloured.