Molecular Orbital Theory

This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Molecular Orbital Theory”.

1. If the sign of the wave function is unchanged when the orbital is reflected about its centre, the orbital is
a) Gerade
b) Ungerade
c) Gerade as well as Ungerade
d) None of the mentioned
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2. The filling of molecular orbital takes place according to
a) The Aufbau Principle
b) Pauli Exculsion Principle
c) Hund’s rule of maximum multiplicity
d) All of the mentioned
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3. Bond Order of O2, F2, N2 respectively are
a) +1, +2, +3
b) +2, +3, +1
c) +2, +1, +3
d) +3, +2, +1
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4. Arrange the following molecules in decreasing bond length.
a) O2 > O2– > O2+ > O22-
b) O22- > O2– > O2 > O2+
c) O22- > O2– > O2+ > O2
d) O2– > O2+ > O22- > O2
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5. Arrange the following molecules in the order of increasing stability.
a) N2+ < N2 < N2– < N22-
b) N22- < N2– < N2 < N2+
c) N22- < N2– = N2+ < N2
d) N2 < N2+ = N2– < N22-
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6. On the basis of molecular orbital theory, select the most appropriate option.
a) The bond order of O2 is 2.5 and it is paramagnetic
b) The bond order of O2 is 1.5 and it is paramagnetic
c) The bond order of O2 is 2 and it is diamagnetic
d) The bond order of O2 is 2 and it is paramagnetic
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7. Which of the following molecule does not exist due to its zero bond order?
a) H2+
b) He2+
c) He2
d) H2–
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8. The relative energies of molecular orbitals in increasing order have been found to be as follows:
(σ1s) < (σ*1s) < (σ2s) < (σ*2s) <[(π2py)(π2pz)] < (σ 2px) < [(π*2py)(π*2pz)] < (σ*2px)
a) For O2 to Ne2
b) For H2 to N2
c) For H2 to Ne2
d) For N2 to Ne2
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9. According to Molecular Orbital Theory, the shape and size of a molecular orbital depends upon
a) Shape and size of the combining atomic orbitals
b) Numbers of the combining atomic orbitals
c) Orientation of the combining atomic orbitals
d) All of the mentioned
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10. Choose the incorrect statement from the following options.
a) In bonding molecular orbital, electron density is low in the region between the nuclei of bonded atoms
b) The energy of antibonding molecular orbital is higher than that of atomic orbitals from which it is formed
c) Every electron in bonding molecular orbital contributes toward stability of the molecule
d) Antibonding takes place when lobes of atomic orbitals have different signs
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