Question 1: Ti(H2O)6]3+ is coloured whereas [Sc(H2O)6]3+ is colourless, though it is a transition metal complex. Explain the observation.
Solution: Ti3+ has one electron in the d-orbital (3d1) which can absorb energy corresponding to yellow wavelength and jump from lower energy level to higher energy level. But Sc3+ has no electron in d-orbital.
Question 2: NiCl4]2– is paramagnetic while (Ni(CO)4] is diamagnetic. Why?
Solution: In [Ni(CO)4], Ni is in zero oxidation state whereas is (NiCl4]2–, Ni is in +2 oxidation state. In the presence of ligand CO, the unpaired electrons of Ni pair up but Cl– being a weak ligand is unable to pair up the unpaired electrons.
Question 3: Calculate the magnetic moment of V3+.
Solution: The electronic configuration of V3+ is [Ar] 4s°3d2. In the d–orbitals there are 2 unpaired electrons
Question 4: Why Sm2+, Eu2+ and Yb2+ ions in solutions are good reducing agents but an aqueous solution of Ce4+ is a good oxidizing agent?
Solution: The most stable oxidation state of lanthanides is +3 hence ions in +2 state tend to change to +3 state by loss of electron and those in+4 state tend to change to +3 state by gain of electron