Question

Among $TiF _{6}^{2-}, CoF _{6}^{2-}, Cu _{2} Cl _{2}$ and $NiCl _{4}^{2-}$ which are colourless species?

• A. $Cu _{2} Cl _{2}$ and $NiCl _{4}^{2-}$
• B. $CoF _{6}^{3-}$ and $NiCl _{4}^{2-}$
• C. $CoF _{6}^{3-}$ and $TiF _{6}^{2-}$
• D. $TiF _{6}^{2-}$ and $Cu _{2} Cl _{2}$

Answer 1

Answer: (D)

Among the given, $Cu ^{+}$in $\left( Cu _{2} Cl _{2}\right)$ and $Ti ^{4+}$ (in $TiF _{6}^{2-}$ ) have no unpaired electrons. So, no $d-d$ transition is possible. Hence, these two are colourless species.