Question

Select correct statement (s).

• A. MnO4– is intense pink c
• B. Cu(I) is diamagnetic while Cu(II) is paramagnetic.
• C. CrO3 is amphoteric oxide.
• D. [Ti(H2O)6]3+ and [Sc(H2O)6]3+ both are coloured in aqueous solution.

Answer 1

Answer: (B)

Cu(I) is diamagnetic while Cu(II) is paramagnetic.

Answer 2

(1) Coloured due to charge transfer from ligand to metal ion.

(2) Valence shell electron configuration of Cu(I) is 3d10 and, therefore, all electrons are paired ; Valence shell electron configuration of Cu(II) is 3d9 and, therefore, one electron is unpaired.

(3) CrO3 is an acid anhydride of chromic acid.

(4) Valence shell electron configuration of Ti3+ is 3d1 and, therefore, has one unpaired electron; so it is coloured. But valence shell electron configuration of Sc3+ is 3d0 and, therefore, it has no unpaired electron; so it is colourless.