question_answer

Magnetic moments of \[Cr(Z=24),\,Mn(Z=25)\] and \[Fe(Z=26)\] are \[x,\,y\] and \[z\] respectively. Hence,

A) \[x=y=z\]

B) \[x=y<z\]

C) \[x<y<z\]

D) \[x>y>z\]

Correct Answer: D

Solution :

[d] \[Cr(24)=1{{s}^{2}},\,2{{s}^{2}},\,2{{p}^{6}},\,3{{s}^{2}},\,3{{p}^{6}},\,4{{s}^{1}},\,3{{d}^{5}}\]

\[Mn\,(25)=1{{s}^{2}},\,2{{s}^{2}},\,2{{p}^{6}},\,3{{p}^{6}},\,4{{s}^{2}},\,3{{d}^{5}}\]

\[Fe(26)=1{{s}^{2}},\,2{{s}^{2}},\,2{{p}^{6}},\,3{{s}^{2}},\,3{{p}^{6}},\,4{{s}^{2}},\,3{{d}^{6}}\]

Magnetic moment \[(\mu )=\sqrt{n(n+2)}\]

where, \[n=\] number of unpaired electrons.

Greater the number of unpaired electrons, greater will be the magnetic moment.