Q. It is an experiment fact that is orange coloured but is yellow. It is further known that total paramagnetic moment of a unpaired electron is due to spin as well as due to nature of orbital, 'd' orbital contributing more than 's' or ' '. Thus the total paramagnetic moment of orange compound is found to be more than that of yellow compound. Then which of the following is correct :

 1901  168 Coordination Compounds Report Error

Solution:

(orange) is tetrahedral because in the unpaired electron is in . But yellow is square planar because the unpaired electron is not in rather in some promoted state 's' or ' '.