Question 1

According to valence bond theory, what is the predicted bond angle in a methane (CH$$_4) $$molecule if only unhybridized atomic orbitals are considered?

Accepted Answer

$$90^\circ$$

Question 2

What is the observed bond angle in methane (CH$$_4$$), and what does this observation suggest about the bonding in methane?

Accepted Answer

$$109.5^\circ$$; the carbon atom uses sp$$^3$$ hybrid orbitals

Question 3

Which of the following best explains why hybrid orbitals form in atoms like carbon?

Accepted Answer

Hybrid orbitals allow for greater overlap with other orbitals, resulting in stronger bonds.

Question 4

How many sigma ($$\sigma) $$and pi ($$\pi) $$bonds are present in a molecule of ethene (C$$_2H$_4$$)?

Accepted Answer

5 $$\sigma$$ bonds and 1 $$\pi$$ bond

Question 5

Which hybridization scheme allows the central atom to form more than four bonds?

Accepted Answer

sp$$^3d$$

Question 6

In the molecule CO$$_2$$, what is the hybridization of the central carbon atom?

Accepted Answer

sp

Question 7

Which of the following statements about molecular orbital (MO) theory is correct?

Accepted Answer

Bonding molecular orbitals are lower in energy than the atomic orbitals from which they are formed.

Question 8

Which molecule or ion has the highest bond order according to MO theory?

Accepted Answer

C$$_2$$

Question 9

What is the bond order of the O$$_2^-$$ ion according to molecular orbital theory?

Accepted Answer

$$1.5$$

Question 10

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

Accepted Answer

$$\sigma$$ bonds result from end-to-end overlap of orbitals, while $$\pi$$ bonds result from side-to-side overlap.

Question 11

In the molecule NH$$_3$$, what is the hybridization of the nitrogen atom?

Accepted Answer

sp$$^3$$

Question 12

Which of the following molecules contains an sp$$^2$$ hybridized central atom?

Accepted Answer

BF$$_3$$

Question 13

Which of the following statements about the bonding in acetylene (C$$_2H$_2) is $$correct?

Accepted Answer

Each carbon atom is sp hybridized and forms two $$\pi$$ bonds and one $$\sigma$$ bond with the other carbon.

Question 14

Which of the following best explains why the bond angle in water (H$$_2O) is $$less than the tetrahedral angle?

Accepted Answer

Lone pairs on oxygen repel bonding pairs more strongly, compressing the bond angle.

Question 15

Which of the following molecules is predicted to be paramagnetic according to MO theory?

Accepted Answer

O$$_2$$

Question 16

How many bonds can a nitrogen atom (electron configuration 2s$$^22p$^3) $$form without hybridization?

Accepted Answer

3

Question 17

Which hybridization scheme allows the formation of at least one $$\pi$$ bond?

Accepted Answer

sp, sp$$^2$$

Question 18

Which of the following best describes the bonding in carbon dioxide (CO$$_2$$)?

Accepted Answer

The carbon atom forms two $$\sigma$$ bonds and two $$\pi$$ bonds using sp hybrid orbitals.

Question 19

Which of the following is a consequence of the large lobe in a hybrid orbital?

Accepted Answer

It allows for greater overlap with other orbitals, resulting in stronger bonds.

Question 20

Which of the following molecules contains both $$\sigma$$ and $$\pi$$ bonds?

Accepted Answer

CO$$_2$$

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

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