Which one of the following shows highest magnetic moment?
Fe2+
Co2+
Cr3+
Ni2+
A.
Fe2+
The paramagnetism or magnetic moment produced due to spin of electrons or unpaired electrons is expressed in terms of Bohr magneton (BM) or μB and given by
Magnetic moment (μ) =√[n(n+2)]BM
where n is the number of unpaired electron, in species. Thus, greater is the number of unpaired electron is an ion greater is its paramagnetic nature.
| Ion | electronic configuration | No. of unpaired e- s |
| Cr3+ | d3 | 3 |
| Fe2+ | d6 | 4 |
| Co2+ | d7 | 3 |
| Ni2+ | d8 | 2 |
As Fe2+ ion has maximum number of unpaired electrons, thus it has highest magnetic moment.
The electronic configuration of Gd2+ is (atomic number of Gd is 64).
[Xe]4f8
[Xe]4f7
[Xe]4f7 5d16s2
[Xe]4f7 5d1
Mn2+ compounds are more stable than Fe2+ compounds towards oxidation to their +3 state, because
Mn2+ is more stable with high 3rd ionisation energy
Mn2+ is bigger in size
Mn2+ has completely filled d-orbital
Mn2+ does not exist
The correct statement is
The earlier members of lanthanoid series resemble calcium in their chemical properties.
The extent of actinoid contraction is almost the same as lanthanoid contraction.
In general, lanthanoid and actinoids do not show variable oxidation states.
Ce4+ in aqueous solution is not known.
Which of the following is a negatively charged bidentate ligand?
Cyano
Ethylene diamine
Acetato
Dimethyl glyoximato
In a transition series, with increase in atomic-number, the paramagnetism
increases gradually
decreases gradually
first increases to a maximum and then decreases
first decreases to a minimum and then increases
The bivalent metal ion having maximum paramagnetic behaviour among the first transition series elements is
Mn2+
Cu2+
Sc2+
Cu+
When a brown compound of Mn (A) is treated with HCl, it gives a gas (B). The gas (B) taken in excess reacts with NH3 to give; an explosive compound (C). The compounds A, B and C respectively are
A - MnO2; B - Cl2; C - NCl3
A - MnO; B - Cl2; C - NH4Cl
A - Mn3O4; B - Cl2; C - NCl3
A - MnO3; B - Cl2; C - NCl2
