question_answer

Which of the following is coloured?

A)  \[T{{i}^{4+}}\]           

B)  \[{{V}^{5+}}\]

C)  \[C{{u}^{+}}\]           

D)  \[C{{u}^{2+}}\]

Correct Answer: D

Solution :

Key Idea: The ion which is having unpaired electron is coloured. Draw all the ions given in choices to find which of them is coloured. [a] \[T{{i}^{4+}}\] \[\because \] It has no unpaired electron] \[\therefore \] It is colourless. [b] \[{{V}^{5+}}\] \[\because \] It has no unpaired electron. \[\therefore \] It is colourless. [c] \[C{{u}^{+}}\] \[\because \,C{{u}^{+}}\] has all electrons paired. \[\therefore \] It is colourless. [d] \[C{{u}^{2+}}\] \[\because \] It has one unpaired electron. \[\therefore \,C{{u}^{2+}}\] is coloured.