Question 1

Which of the following statements best explains why molecular orbital (MO) theory is necessary to account for the paramagnetism of O$$_2$$?

Accepted Answer

MO theory allows for electron delocalization and predicts unpaired electrons in O$$_2$$, matching its observed paramagnetic behavior.

Question 2

According to valence bond theory, what is the main requirement for a chemical bond to form between two atoms?

Accepted Answer

The atomic orbitals must overlap and the electrons must be spin-paired.

Question 3

Which type of bond is formed by the sideways overlap of unhybridized p orbitals?

Accepted Answer

A $$\pi$$ bond

Question 4

What is the bond order of the H$$_2$$ molecule according to molecular orbital theory?

Accepted Answer

$$1$$

Question 5

Which hybridization is associated with a central atom that has four electron groups and a tetrahedral geometry?

Accepted Answer

$$sp^3$$

Question 6

A molecule with a linear geometry and two electron groups around the central atom will have which type of hybridization?

Accepted Answer

$$sp$$

Question 7

Why does the molecule He$$_2$$ not exist under normal conditions?

Accepted Answer

Its bond order is $$0$$, meaning no net bonding occurs.

Question 8

Which of the following is a limitation of Lewis theory when predicting molecular properties?

Accepted Answer

Lewis theory cannot predict the magnetic behavior of molecules such as O$$_2.$$

Question 9

What is the bond order of the NO molecule according to molecular orbital theory?

Accepted Answer

$$2.5$$

Question 10

Which statement about $$\sigma$$ and $$\pi$$ bonds is correct?

Accepted Answer

$$\sigma$$ bonds result from end-to-end overlap and are generally stronger than $$\pi$$ bonds.

Question 11

Which hybridization scheme is expected for the central atom in BrF$$_3$$?

Accepted Answer

$$sp^3d$

Question 12

In molecular orbital theory, what is the effect of electrons occupying antibonding orbitals?

Accepted Answer

They destabilize the molecule by increasing its energy.

Question 13

Which of the following molecules is predicted to be paramagnetic by molecular orbital theory?

Accepted Answer

O$$_2$$

Question 14

What is the bond order of the He$$_2^+$$ ion?

Accepted Answer

$$\frac{1}{2}$$

Question 15

Which statement best describes the concept of hybridization in valence bond theory?

Accepted Answer

Hybridization is the mixing of atomic orbitals to form new degenerate orbitals suitable for bonding.

Question 16

A carbon atom in ethyne (C$$_2H$_2) is $$expected to have which hybridization?

Accepted Answer

$$sp$$

Question 17

Which of the following is true regarding the number of molecular orbitals formed from a set of atomic orbitals?

Accepted Answer

The number of molecular orbitals equals the number of atomic orbitals combined.

Question 18

Which molecule has a bond order of $$3$$ according to molecular orbital theory?

Accepted Answer

N$$_2$$

Question 19

Which of the following best describes the difference between valence bond theory and molecular orbital theory?

Accepted Answer

Valence bond theory localizes electrons between atoms, while molecular orbital theory delocalizes electrons over the entire molecule.

Question 20

Which of the following molecules is expected to have $$sp^3d^2$ hybridization at its central atom?

Accepted Answer

SF$$_6$$

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

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