question_answer

The aqueous solution containing which one of the following ions will be colourless? (Atomic number: (\[\operatorname{Sc} = 21, Fe = 26\], \[\operatorname{Ti} = 22, Mn = 25)\]

A) \[S{{c}^{3+}}\]         

B)        \[F{{e}^{2+}}\]

C) \[T{{i}^{3+}}\]          

D)        \[M{{n}^{2+}}\]

Correct Answer: A

Solution :

\[{{\operatorname{Sc}}^{3+}}\to \,\,3{{d}^{6}}\,4{{s}^{0}}\] \[{{\operatorname{Fe}}^{2+}}\to 3{{d}^{6}}\,4{{s}^{0}}\] \[{{\operatorname{Ti}}^{3+}}\to \,3{{d}^{1}}\,4{{s}^{0}}\] \[M{{n}^{2+}}\to 3{{d}^{5}}\,4{{s}^{0}}\]   In \[S{{c}^{3+}}\] there is/are no unpaired electrons. So the aqueous solution of \[S{{c}^{3+}}\] will be colourless.