Atomic number of Mn, Fe, Co and Ni are 25, 26, 27 and 28 respectively. Which of the following outer orbital octahedral complexes have the same number of unpaired electrons?

(a) MnCl63-(b) FeF63-(c) CoF63-(d) NiNH362+

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

Molecular orbital electronic configuration of Mn3+in MnCl63- is

Number of unpaired electrons =4

Magnetic property = Paramagnetic

Molecular orbital electronic configuration of Co3+in CoF63- is

 

Number of unpaired electrons =4

Magnetic property = Paramagnetic

Molecular orbital electronic configuration of Fe3+in FeF63- is 

 

Number of unpaired electrons =4

Magnetic property = Paramagnetic

Molecular orbital electronic configuration of Ni2+ in NiNH362+ is 

 

Number of unpaired electrons =4

Magnetic property = Paramagnetic

Thus, MnCl63- and CoF63- are paramagnetic having four electrons each. 

Hence, correct choices are (a) (c).