question_answer

The magnetic moment of \[{{M}^{x\,+}}\] (atomic number = 25) is \[\sqrt{15}\,BM\]. Then, the oxidation number \[x\] of M is

A)  3               

B)  4

C)  2              

D)  1

Correct Answer: B

Solution :

The electronic configuration of \[{{M}^{x+}}(Z=25)\] is \[1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{2}},3{{p}^{6}},3{{d}^{5}},4{{s}^{2}}\] Magnetic moment \[=\sqrt{n\,(n+2)}\,BM\] \[=\sqrt{5\,(5+2)}\,BM=\sqrt{35}\,BM\] Given, magnetic moment \[=\sqrt{15}\,BM=\sqrt{3\,(3+2)}\,BM\] Hence, unpaired electrons = 3 \[\therefore \] The oxidation number \[x\] is 4.