question_answer

The paramagnetic element is :

A)  \[N{{i}^{2+}}\]

B)  \[S{{c}^{3+}}\]

C)  \[C{{u}^{+}}\]

D)  \[Z{{n}^{2+}}\]

Correct Answer: A

Solution :

Key Idea: The ions having unpaired electrons are paramagnetic. The, ions having paired electrons are diamagnetic. [a] \[N{{i}^{2+}}=1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{2}},3{{p}^{6}},4{{s}^{0}},3{{d}^{8}}\]                 \[\therefore \] It has 2 unpaired electrons and is paramagnetic. [b] \[S{{c}^{3+}}=1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{2}},3{{p}^{6}},4{{s}^{0}},3{{d}^{0}}\] \[\therefore \] It has no unpaired electrons and is diamagnetic. [c] \[C{{u}^{+}}=1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{2}},3{{p}^{6}},4{{s}^{0}},3{{d}^{10}}\] It has no unpaired electrons and is diamagnetic. [d] \[Z{{n}^{2+}}=1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{2}},3{{p}^{6}},4{{s}^{0}},3{{d}^{10}}\] \[\therefore \] It has no unpaired electrons and is diamagnetic.