Which of the following compounds is coloured ? (AIIMS 2008)

It may be noted that transition metal ions that have unpaired electrons undergo the electronic transition. These electrons absorbed visible radiation and excite to higher energy levels and emit complementary radiations. Herein 3 TiCl , titanium is in +3 an oxidation state. It contains 1 electron which undergoes electronic excitation. It is a coloured compound. Similarly, in 3 FeCl , iron is in +3 an oxidation state. It contains 5 electrons in d-orbital which undergoes a d-d transition. Therefore it is a yellow-coloured compound. Cobalt exhibits +2 an oxidation state in 2 CoCl 2+ Co ion conta