Question

Which one of the following statements is INCORRECT about a complex of a divalent ion with atomic number 25? (BM = Bohr Magneton)

A. Complex with weak field ligands in tetrahedral geometry has a magnetic moment of 1.73 BM.

B. Complex with weak field ligands in tetrahedral geometry has a magnetic moment of 5.92 BM.

C. Complex with strong field ligands in octahedral geometry has a magnetic moment of 1.73 BM.

D. Complex with weak field ligands in octahedral geometry has a magnetic moment of 5.92 BM.

Answer 1

As we know, 

Mn has atomic number 25.

∴ Mn⁺² = [Ar]3d⁵

Mn⁺² =     in weak field ligand

Mn⁺² =      in strong field ligand

Therefore,

magnetic moment in weak field ligand -

\(\mu = \sqrt{n(n + 2)} B.M.\)

\(\mu = \sqrt{5(5 + 2)}\)

\(\mu = \sqrt{35}\)

\(\mu = 5.92 B.M.\)

Magnetic moment in strong field ligand -

\(\mu = \sqrt{n(n + 2)} B.M.\)

\(\mu = \sqrt{1(1+2)}\)

\(\mu = \sqrt3 \)

\(\mu = 1.73 B.M.\)

Thus, in strong field, octahedral geometry magnetic moment will be 1.73 BM and in weak field Octahedral geometry magnetic moment will be 5.92 B.M. and tetrahedral geometry. Complex has magnetic moment 5.92 B.M.

Statement A is incorrect.

Hence, option A is right answer.