Question 1

Which of the following best explains why liquid oxygen is attracted to a magnetic field?

Accepted Answer

Oxygen molecules have unpaired electrons in their molecular orbitals, making them paramagnetic.

Question 2

According to valence bond theory, what is the main criterion for the formation of a covalent chemical bond?

Accepted Answer

The overlap of half-filled atomic orbitals from two atoms.

Question 3

Which hybridization and geometry are expected for the central carbon atom in methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

sp$$^3$$ hybridization; tetrahedral geometry

Question 4

Which of the following statements about double bonds is correct according to valence bond theory?

Accepted Answer

Rotation about a double bond is restricted due to the presence of a pi bond.

Question 5

What is the bond order of molecular oxygen ($$\mathrm{O_2$}) $$according to molecular orbital theory?

Accepted Answer

$$2$$

Question 6

Which of the following best describes an antibonding molecular orbital?

Accepted Answer

It is formed by destructive interference of atomic orbitals and has a node between nuclei.

Question 7

A molecule has three electron groups around its central atom. What is the expected hybridization and geometry?

Accepted Answer

sp$$^2$$ hybridization; trigonal planar geometry

Question 8

Which of the following molecules is predicted to have sp hybridization at its central atom?

Accepted Answer

Carbon dioxide ($$\mathrm{CO_2$})$$

Question 9

Given the molecular orbital diagram for $$\mathrm{N_2$}$$, what is the correct bond order and magnetic property?

Accepted Answer

Bond order $$= 3$$; diamagnetic

Question 10

Which of the following best explains why $$\mathrm{F_2$}$$ has a weaker bond than $$\mathrm{N_2$}$$?

Accepted Answer

$$\mathrm{F_2$}$$ has a lower bond order due to more electrons occupying antibonding orbitals.

Question 11

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

Accepted Answer

As bond order increases, bond length decreases.

Question 12

In the context of molecular orbital theory, what is the effect of filling antibonding orbitals with electrons?

Accepted Answer

It decreases bond order and weakens the bond.

Question 13

Which of the following best describes the hybridization and geometry of the central atom in $$\mathrm{BF_3$}$$?

Accepted Answer

sp$$^2$$ hybridization; trigonal planar geometry

Question 14

Which of the following statements about benzene ($$\mathrm{C_6H_6}) is $$correct according to molecular orbital theory?

Accepted Answer

The $$\pi$$ electrons are delocalized over the entire ring, resulting in equal bond lengths.

Question 15

A molecule has a bond order of $$0. $$What does this indicate about the molecule?

Accepted Answer

The molecule is not stable and does not exist under normal conditions.

Question 16

Which of the following is the correct formula for calculating bond order using molecular orbital theory?

Accepted Answer

$$	ext{Bond order} = \frac{	ext{number of electrons in bonding MOs} - 	ext{number of electrons in antibonding MOs}}{2}$$

Question 17

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

Accepted Answer

A $$\sigma$$ bond is formed by head-on overlap of orbitals, while a $$\pi$$ bond is formed by side-on overlap.

Question 18

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

Accepted Answer

$$\mathrm{O_2$}$$

Question 19

Which of the following is a limitation of valence bond theory that is addressed by molecular orbital theory?

Accepted Answer

Valence bond theory cannot explain electron delocalization across multiple atoms.

Question 20

In the molecule ozone ($$\mathrm{O_3$}$$), what does molecular orbital theory explain that valence bond theory cannot?

Accepted Answer

The delocalization of electrons over all three oxygen atoms.

Chapter 6: Chemical Bonding II - Valence Bond Theory and Molecular Orbital Theory

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