Molecular Orbital Theory (Its Important features. LCAOs, types of molecular orbitals (bonding, antibonding), sigma and pi-bonds, molecular orbital electronic configurations of homonuclear diatomic molecules, the concept of bond order, bond length, and bond energy ) NEET Questions

Physical Chemistry - Chemical Bonding and Molecular Structure

Molecular Orbital Theory (Its Important features. LCAOs, types of molecular orbitals (bonding, antibonding), sigma and pi-bonds, molecular orbital electronic configurations of homonuclear diatomic molecules, the concept of bond order, bond length, and bond energy ) MCQ Questions


7.
Compared to combining atomic orbitals, the energy of bonding molecular orbital is:
A.
Zero
B.
Same
C.
Lower
D.
Higher
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ANSWER :
C. Lower
8.
The energy of antibonding molecular orbital is:
A.
Always zero
B.
Lower than parent atomic orbitals
C.
Higher than parent atomic orbitals
D.
Equal to parent atomic orbitals
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ANSWER :
C. Higher than parent atomic orbitals
9.
LCAO stands for:
A.
Localized Combination of Atomic Orbitals
B.
Linear Coupling of Atomic Oxygen
C.
Loose Combination of Atomic Operators
D.
Linear Combination of Atomic Orbitals
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ANSWER :
D. Linear Combination of Atomic Orbitals
10.
In LCAO method, the atomic orbitals can be combined by:
A.
Only subtraction
B.
Both addition and subtraction (giving bonding and antibonding MOs)
C.
Multiplication
D.
Only addition
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ANSWER :
B. Both addition and subtraction (giving bonding and antibonding MOs)
11.
What are the conditions for atomic orbitals to combine via LCAO method?
A.
Any orbital can combine with any other
B.
Same or nearly same energy, same symmetry about molecular axis, and significant overlap
C.
Same energy and same symmetry
D.
Different energies and same shape
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ANSWER :
B. Same or nearly same energy, same symmetry about molecular axis, and significant overlap
12.
Which of the following pairs of orbitals will NOT combine to form molecular orbitals?
A.
2pz and 2px (different symmetries)
B.
2s and 2s
C.
1s and 1s
D.
2pz and 2pz (along z-axis)
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ANSWER :
A. 2pz and 2px (different symmetries)