The magnetic moments of few transition metal ions are given below :
`{:("Metal ion",,,"Magnetic moment (BM)"),(Sc^(3+),,,0.00),(Cr^(2+),,,4.90),(Ni^(2+),,,2.84),(Ti^(3+),,,1.73):}`
(At. no. Sc = 21, Ti = 22, Cr = 24, Ni = 28)
Which of the given metal ions :
(i) has the maximum number of unpaired electrons ?
(ii) forms colourless aqueous solution ?
(iii) exhibits the most stable +3 oxidation state ?

Explanation

(i) As `Cr^(2+)` shows the maximum magnetic moment, it has the maximum number of unpaired electrons.
(ii) The configuration of `Sc^(3+)` ion is `1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6)`. As all the orbitals are completely filled, there is no possibility of excitation of electrons. It forms a colourless aqueous solution.
(iii) Again because of completely filled orbitals, `Sc^(3+)` shows the most stable +3 oxidation state.