The paramagnetism of $$\text{O}_2$$

$$\text{F}_2 \u003c \text{O}_2 \u003c \text{N}_2$$

Question 1

Which of the following statements best describes the main idea of Valence Bond (VB) Theory?

Accepted Answer

VB Theory explains molecular bonding by considering the overlap of atomic orbitals to form localized bonds between atoms.

Question 2

According to VSEPR theory, what is the predicted molecular geometry of $$	ext{SF}_4$$?

Accepted Answer

See-saw

Question 3

Which of the following molecules is predicted to be paramagnetic based on its molecular orbital (MO) diagram?

Accepted Answer

$$	ext{O}_2$$

Question 4

A molecule has a bond order of zero according to MO theory. What does this imply about the molecule?

Accepted Answer

The molecule is unstable and will not exist under normal conditions.

Question 5

Which of the following best explains why $$	ext{CO}_2 is a $$nonpolar molecule, even though it contains polar bonds?

Accepted Answer

The molecule is linear, so the bond dipoles cancel each other out.

Question 6

Which of the following is the correct bond order for $$	ext{N}_2$$ according to MO theory?

Accepted Answer

$$3$$

Question 7

A student is asked to predict the bond angle in $$	ext{NH}_3$$ using VSEPR theory. Which of the following is the best answer?

Accepted Answer

$$107^\circ$$

Question 8

Which of the following statements about hybridization is correct?

Accepted Answer

An atom with four electron domains around it will be $$sp^3$$ hybridized.

Question 9

Which of the following best describes the difference between sigma ($$\sigma) $$and pi ($$\pi) $$bonds?

Accepted Answer

$$\sigma$$ bonds result from head-on overlap of orbitals, while $$\pi$$ bonds result from side-on overlap.

Question 10

Which of the following molecules has a bond angle closest to $$120^\circ$$?

Accepted Answer

$$	ext{BF}_3$$

Question 11

A molecule has the following MO electron configuration: $$\sigma_{2s}^2\,\sigma_{2s}^*{}^2\,\pi_{2p}^4\,\sigma_{2p}^2. $$What is its bond order?

Accepted Answer

$$2$$

Question 12

Which of the following is a key prediction of Molecular Orbital (MO) Theory that cannot be explained by Valence Bond (VB) Theory?

Accepted Answer

The paramagnetism of $$	ext{O}_2$$

Question 13

Which of the following best describes the HOMO-LUMO gap in a molecule?

Accepted Answer

The energy difference between the highest occupied and lowest unoccupied molecular orbitals.

Question 14

Which of the following molecules is expected to have the shortest bond length?

Accepted Answer

$$	ext{N}_2$$

Question 15

Which of the following is a consequence of a small HOMO-LUMO gap in a molecule?

Accepted Answer

The molecule can absorb lower energy (longer wavelength) light.

Question 16

Which of the following best explains why $$	ext{H}_2	ext{O}$$ has a bent molecular geometry?

Accepted Answer

The two lone pairs on oxygen repel the bonding pairs, resulting in a bent shape.

Question 17

Which of the following is the correct order of increasing bond energy for the following molecules: $$	ext{F}_2$$, $$	ext{O}_2$$, $$	ext{N}_2$$?

Accepted Answer

$$	ext{F}_2 \u003c 	ext{O}_2 \u003c 	ext{N}_2$$

Question 18

A chemist uses UV-Vis spectroscopy to study a molecule. Which molecular property is most directly related to the absorption wavelength observed?

Accepted Answer

The HOMO-LUMO gap

Question 19

Which of the following is a real-world application of understanding molecular orbital theory?

Accepted Answer

Designing solar cells for efficient energy conversion

Question 20

Which of the following statements about the relationship between bond order and bond length is correct?

Accepted Answer

As bond order increases, bond length decreases.

Study Guide: Chemical Bonding II – Molecular Shapes, Valence Bond Theory, and Molecular Orbital Theory

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