Q. In $ TiF_{6}^{2-},CoF_{6}^{3-},C{{u}_{2}}C{{l}_{2}} $ and $ NiCl_{4}^{2-} $ the colourless species is (Atomic number Ti = 22, Co = 27, Cu = 29, Ni = 28)
Rajasthan PETRajasthan PET 2006
Solution:
$ TiF_{6}^{2-},CoF_{6}^{3-},C{{u}_{2}}C{{l}_{2}} $ and $ NiCl_{4}^{2-} $ give $ T{{i}^{4+}},C{{o}^{3+}},C{{u}^{+}} $ and $ N{{i}^{2+}} $ ions respectively.
$ T{{i}^{4+}}=3{{d}^{0}},{{45}^{0}} $
$ C{{o}^{3+}}=3{{d}^{6}},{{45}^{0}} $
$ C{{u}^{+}}=3{{d}^{10}},{{45}^{0}} $
$ N{{i}^{2+}}=3{{d}^{8}},{{45}^{0}} $
$ TiF_{6}^{2-} $ and $ C{{u}_{2}}C{{l}_{2}} $ species are colourless due to the absence to unparied electron in $ T{{i}^{4+}} $ and $ C{{u}^{+}} $ ions.
