Question

Which one of the following sets correctly represents the increase in the paramagnetic property of the ions ?

• A. $ Cu^{2+} > V^{2+} > Cr^{2+} > Mn^{2+}$
• B. $ Cu^{2+} < Cr^{2+} < V^{2+} < Mn^{2+}$
• C. $ Cu^{2+} < V^{2+} < Cr^{2+} < Mn^{2+}$
• D. $ V^{2+} < Cu^{2+} < Cr^{2+} < Mn^{2+}$

Answer 1

Answer: (C)

Paramagnetic property depends upon the number of unpaired electrons. Higher the number of unpaired electrons, higher the paramagnetic property will be.
$Cu^{2+} = [Ar] \, 3d^9$, no. of unpaired electrons $= 1$
$V^{2+} = [Ar] \, 3d^3$, no. of unpaired electrons $= 3$
$Cr^{2+} = [Ar] \, 3d^4$, no. of unpaired electrons $= 4$
$Mn^{2+} = [Ar] \, 3d^5$, no. of unpaired electrons $= 5$
Hence, correct order is -
$Cu^{2+} < V^{2+} < Cr^{2+} < Mn^{2+}$