question_answer

            Which of the following has more unpaired d-electrons?                                                                   

A)              \[Z{{n}^{+}}\]  

B)                                        \[F{{e}^{2+}}\]                                

C)                    \[{{N}^{3+}}\]                                      

D)              \[C{{u}^{+}}\]

Correct Answer: B

Solution :

                               \[Zn_{(At.\,No.\,=30)}^{+}=1{{s}^{2}},\,2{{s}^{2}}2{{p}^{6}},\,3{{s}^{2}}3{{p}^{6}}3{{d}^{10}},\,4{{s}^{1}}\]                 \[Fe_{(At.\,No.\,26)}^{2+}=1{{s}^{2}},\,2{{s}^{2}}2{{p}^{6}},\,3{{s}^{2}}3{{p}^{6}}3{{d}^{6}}\]                                 \[N_{(At.\,No.=7)}^{3+}=1{{s}^{2}},2{{s}^{2}}\,2{{p}^{0}}\]                 \[Cu_{(At.\,No=29)}^{+}=1{{s}^{2}},2{{s}^{2}}2{{p}^{6}},3{{s}^{2}}3{{p}^{6}}3{{d}^{10}}\]             So, maximum number of unpaired electrons are present in \[F{{e}^{2+}}\].