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