Answer 1

Factors responsible for colour of a transition metal ions :
(a) The presence of incompletely filled d – orbitals in metal ions.                                [1/2 M]
(b) The presence of unpaired electrons in d – orbitals.                                                 [1/2 M]
(c) d – d transition of electrons due to absorption of radiation in the visible region.   [1/2 M]
(d) Type of hybridisation in metal ion in the complex.                                                  [1/2 M]
(e) Geometry of the complex containing transition metal ion.