Question 1

Which of the following statements best describes the difference between a polar covalent bond and an ionic bond?

Accepted Answer

A polar covalent bond involves unequal sharing of electrons due to differences in electronegativity, while an ionic bond involves the transfer of electrons from one atom to another.

Question 2

Given the electronegativities: C = 2.5, O = 3.5, H = 2.1, which bond is the most polar?

Accepted Answer

$$\mathrm{O-H}$$

Question 3

Which molecule would you expect to have the largest dipole moment based on Table 2.1?

Accepted Answer

$$\mathrm{NaCl}$$

Question 4

What is the formal charge on the oxygen atom in dimethyl sulfoxide $$(\mathrm{(CH_3$)_2SO}) as $$shown in the images?

Accepted Answer

$$-1$$

Question 5

Which of the following best explains why benzene $$(\mathrm{C_6H_6}) is $$more stable than any individual resonance form?

Accepted Answer

Because the resonance hybrid allows for delocalization of electrons, lowering the overall energy.

Question 6

Which of the following is a Brønsted–Lowry acid?

Accepted Answer

A substance that donates a proton $$(\mathrm{H^+}).$$

Question 7

If the $$pK_a of $$acetic acid is $$4.76$$ and the $$pK_a of $$water is $$15.74$$, which is the stronger acid?

Accepted Answer

Acetic acid, because it has a lower $$pK_a.$$

Question 8

Which of the following best describes a Lewis acid?

Accepted Answer

A substance that accepts an electron pair.

Question 9

Which of the following interactions is primarily responsible for the secondary structure of DNA?

Accepted Answer

Hydrogen bonds

Question 10

A molecule has a net dipole moment of zero. Which of the following is the most likely explanation?

Accepted Answer

The molecule is symmetrical, so the bond dipoles cancel.

Question 11

Which of the following best describes the inductive effect?

Accepted Answer

The shifting of electrons in a bond in response to the electronegativity of nearby atoms.

Question 12

Which of the following organic compounds is most likely to act as a Lewis base?

Accepted Answer

Methanol $$(\mathrm{CH_3OH})$$

Question 13

Which of the following statements about resonance forms is FALSE?

Accepted Answer

A molecule with resonance forms alternates rapidly between each form.

Question 14

Which of the following best explains why nonpolar substances are insoluble in water?

Accepted Answer

Nonpolar substances cannot form hydrogen bonds with water.

Question 15

Which of the following is the correct expression for the dipole moment $$\mu of a $$molecule?

Accepted Answer

$$\mu = Q 	imes r$$

Question 16

Which of the following best describes the relationship between $$K_a$$ and $$pK_a$$?

Accepted Answer

$$pK_a = -\log K_a$$

Question 17

Which of the following is a real-world example of a Lewis acid-base reaction?

Accepted Answer

The reaction of boron trifluoride $$(\mathrm{BF_3$})$$ with diethyl ether to form an acid-base complex.

Question 18

Which of the following molecules would you expect to have the strongest hydrogen bonding interactions?

Accepted Answer

$$\mathrm{CH_3CH_2OH} ($$ethanol)

Question 19

Which of the following best describes the effect of resonance on the acidity of a molecule?

Accepted Answer

Resonance stabilizes the conjugate base, making the acid stronger.

Polar Covalent Bonds, Acids, and Bases: Structure, Polarity, and Noncovalent Interactions

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