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?

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

Molecular orbital electronic configuration of Mn

Number of unpaired electrons =4

Magnetic property = Paramagnetic

Molecular orbital electronic configuration of

Number of unpaired electrons =4

Magnetic property = Paramagnetic

Molecular orbital electronic configuration of  is

Number of unpaired electrons =4

Magnetic property = Paramagnetic

Molecular orbital electronic configuration of  is

Number of unpaired electrons =4

Magnetic property = Paramagnetic

Thus,  are paramagnetic having four electrons each.

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