Multiple Choice QuestionsAn element with atomic number 21 is a
halogen
representative element
transition element
alkali metal
Mercury is a liquid metal because
it has a completely filled s orbital
it has a small atomic size
it has a completely filled d orbital that prevents d-d overlapping of orbitals
it has a completely filled d orbital that causes d-d overlapping
In chromite ore, the oxidation number of iron, and chromium are respectively
+3,+2
+3,+6
+2,+6
+2,+3
In chromite ore, the oxidation number of iron and chromium are respectively
+3, +2
+3, +6
+2, +6
+2, +3
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
Which of the following is a negatively charged bidentate ligand?
Cyano
Ethylene diamine
Acetato
Dimethyl glyoximato
The electronic configuration of Cu2+ ion is
[Ar] 3d8 4s1
[Ar] 3d9 4s0
[Ar] 3d7 4s2
[Ar] 3d8 4s0
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.
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