Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of the following metallic ions have almost same spin only magnetic moment?
(a)Co2+(b)Cr2+(c)Mn2+(d)Cr3+

Choose the correct option
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)

Electronic configuration of    Co2+=(Ar)3d7  ; Number of unpaired electrons = 3
Electronic configuration of  Cr2+=(Ar)3d4  ; Number of unpaired electrons = 4
Electronic configuration of    Mn2+=(Ar)3d5  ; Number of unpaired electrons = 5
Electronic configuration of   Cr3+=(Ar)3d3  ; Number of unpaired electrons = 3
 
Hence, it is clearly seen that both   have same number of unpaired electrons, i.e, 3.