Question 1

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

Accepted Answer

A $$\sigma$$ bond forms from direct, head-on overlap of orbitals between two nuclei, while a $$\pi$$ bond forms from side-by-side overlap of unhybridized p orbitals.

Question 2

What is the hybridization of the central atom in $$\mathrm{$$SeF_4$$}$$?

Accepted Answer

$$sp^3d$

Question 3

How many $$\sigma$$ and $$\pi$$ bonds are present in a molecule of $$\mathrm{C_2H_2} ($$ethyne/acetylene)?

Accepted Answer

3 $$\sigma$$ and 2 $$\pi$$ bonds

Question 4

Which of the following molecules exhibits delocalized $$\pi$$ bonding (resonance)?

Accepted Answer

$$\mathrm{SO_3$}$$

Question 5

A molecule has a central atom with three electron regions and no lone pairs. What is the expected hybridization and ideal bond angle?

Accepted Answer

$$sp^2$$, 120^\circ$

Question 6

Which of the following molecules contains one or more $$\pi$$ bonds? $$\mathrm{F_2$}$$, $$\mathrm{CO}$$, $$\mathrm{H_2O}$$, $$\mathrm{CH_3COCH_3}$$, $$\mathrm{CO_2$}$$

Accepted Answer

$$\mathrm{CO}$$, $$\mathrm{CH_3COCH_3}$$, and $$\mathrm{CO_2$}$$

Question 7

What is the molecular geometry and polarity of $$\mathrm{NI_3$}$$?

Accepted Answer

Trigonal pyramidal, polar

Question 8

Which hybrid orbitals are used by the central atom in $$\mathrm{$$ICl_2$$^-}$$?

Accepted Answer

$$sp^3d$

Question 9

In the molecule $$\mathrm{CH_3COCH_3} ($$acetone), how many $$\sigma$$ and $$\pi$$ bonds are present?

Accepted Answer

11 $$\sigma$$, 1 $$\pi$$

Question 10

Which of the following best explains why all C–C bonds in benzene are the same length?

Accepted Answer

Benzene has delocalized $$\pi$$ electrons, resulting in resonance and equal bond lengths.

Question 11

A central atom has six electron regions. What is its hybridization and ideal bond angle?

Accepted Answer

$$sp^3d^2$, 90^\circ$$

Question 12

Which of the following is true about the bonding in $$\mathrm{CO_2$}$$?

Accepted Answer

Each C=O bond consists of one $$\sigma$$ and one $$\pi$$ bond.

Question 13

Which of the following molecules is expected to be nonpolar based on its geometry and bond dipoles?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 14

How many unhybridized p orbitals are present on each carbon atom in ethene ($$\mathrm{C_2H_4}$$)?

Accepted Answer

1

Question 15

Which of the following best describes the bonding in $$\mathrm{SO_3$}$$?

Accepted Answer

The $$\pi$$ electrons are delocalized over all three S–O bonds.

Question 16

A molecule has a central atom with five electron regions. What is the expected hybridization and electron group geometry?

Accepted Answer

$$sp^3d$, trigonal bipyramidal

Question 17

Which of the following is a correct statement about hybridization?

Accepted Answer

Hybridization is determined by the number of electron regions around the central atom.

Question 18

In the molecule $$\mathrm{CH_2$=CH_2$} ($$ethene), what is the hybridization of each carbon atom?

Accepted Answer

$$sp^2$$

Question 19

Which of the following molecules has the greatest number of $$\pi$$ bonds?

Accepted Answer

$$\mathrm{C_2H_2}$$

Question 20

Which of the following best describes the bonding in a triple bond?

Accepted Answer

One $$\sigma$$ and two $$\pi$$ bonds

Advanced Theories of Covalent Bonding: Hybridization, Sigma and Pi Bonds, and Resonance

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