Ncert Exercises & Solutions

Atomic number of Mn Fe and Co are 25, 26 and 27 respectively. Which of the following inner orbital octahedral complex ions are diamagnetic?

a. ${[Co {({NH}_{3})}_{6}]}^{3 +}$

b. ${[Mn {(CN)}_{6}]}^{3 -}$

c. ${[F e {(C N)}_{6}]}^{4 -}$

d. ${[Fe {(C N)}_{6}]}^{3 -}$

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

Molecular orbital electronic configuration of CO³⁺ in ${[Co {({NH}_{3})}_{6}]}^{3 +}$

Number of unpaired electron=0

Magnetic property = Diamagnetic

Molecular orbital electronic configuration of ${Mn}^{3 +} in {[MN {(CN)}_{6}]}^{3 -}$

Number of unpaired electron=2

Magnetic property = Paramagnetic

Molecular orbital electronic configuration of $F e^{2 +} i n {[F e {(C N)}_{6}]}^{4 -}$ is

Number of unpaired electron=2

Magnetic property = Diamagnetic

Molecular orbital electronic configuration of ${Fe}^{3 +} in {[Fe ({NN}_{6}]}^{3 -}$

Number of unpaired electron = 2

Magnetic property = Paramagnetic

Thus, ${[Co {({NH}_{3})}_{6}]}^{3 +}$ and ${[F e {(C N)}_{6}]}^{4 -}$ are diamagnetic.

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