Paramagnetism is a property due to the presence of unpaired electrons. In case of transition metals, as they contain unpaired electrons in the `(n-1)` d orbitals , most of the transition metal ions and their compounds are paramagnetic.Paramagnetism increases with increases in number of unpaired electrons. Magnetic moment is calculated from 'spin only formula' `Vz`
`mu=sqrt(n(n+2)) B.M n="number of unpaired electrons"`
Similarly the colour of the compounds of transition metals may be attributed to the presence of incomplete `(n-1)` d sub-shell. When an electron from a lower energy of d-orbitals is excited to a higher energy d-orbital, the energy of excitation corresponds to the frequency of light absorbed. This frequency generally lies in the visible region. The colour observed corresponds to complementary colour of the light observed. The frequency of the light absorbed is determined by the nature of the ligand.
Identify the correct statement.

Options

A. `Mn^(2+)` has the highest paramagnetism amongst the bivalent cations of the `I^(st)` transition series
B. The coloured ions or compounds of transition elements are due to d-d transition, polarisation of anion and change transfer spectrum
C. In 3 d series the paramagnetic character first increase to maximum & then starts decreasing
D. None of these

Answer

D

Explanation

Has five unpaired electrons in 3d-sub shell. (B) is a obvious fact (C ) number of unpaired electrons first increases to five and then pairing begins, so number of unpaired electrons decreases.