Out of TiF62-, CoF63-, Cu2Cl2 and NiCl42- (Z of Ti = 22, Co= 27, Cu = 29, Ni =28) the colourless species are
-
TiF62- and CoF63-
-
Cu2Cl2 and NiCl42-
-
TiF62- and Cu2Cl2
-
CoF63- and NiCl42-
C.
TiF62- and Cu2Cl2
In Cu2Cl2, Cu is present as Cu+
electronic configuration of Cu+ [Ar] 3d10 4s0
thus, due to the absence of a unpaired electron, Cu2Cl2 is colourless.
In TiF62-, Ti present as Ti4+
Ti4+ = [Ar] 3d0 4s0
Hence, TiF62- is colourless.