Question 1

Which of the following best explains why water has a much higher boiling point than methane ($$\mathrm{CH_4$}$$), even though both are small molecules?

Accepted Answer

Water forms hydrogen bonds, which are much stronger than the London dispersion forces present in methane.

Question 2

Which type of intermolecular force is present in all molecules, regardless of their polarity?

Accepted Answer

London dispersion forces (LDF)

Question 3

A student mixes ethanol ($$\mathrm{C_2H_5OH}) $$and water. Which intermolecular forces are present between the molecules in the mixture?

Accepted Answer

Hydrogen bonding, dipole-dipole, and London dispersion forces

Question 4

Which of the following molecules can form hydrogen bonds with itself?

Accepted Answer

$$\mathrm{NH_3$}$$

Question 5

Why does sodium chloride ($$\mathrm{NaCl}) $$have a much higher melting point than water?

Accepted Answer

Ionic bonds in $$\mathrm{NaCl}$$ are much stronger than hydrogen bonds in water.

Question 6

Which of the following statements about London dispersion forces (LDF) is correct?

Accepted Answer

LDF are present in all molecules, but are the only intermolecular force in nonpolar molecules.

Question 7

Which molecule would you expect to have the highest boiling point: $$\mathrm{CH_3OH}$$, $$\mathrm{CH_4$}$$, $$\mathrm{CO_2$}$$, or $$\mathrm{C_2H_6}$$?

Accepted Answer

$$\mathrm{CH_3OH}$$, because it can form hydrogen bonds.

Question 8

Which of the following best describes why oil does not dissolve in water?

Accepted Answer

Oil is nonpolar and cannot form hydrogen bonds with water.

Question 9

Which of the following molecules is nonpolar?

Accepted Answer

$$\mathrm{$$CCl_4$$}$$

Question 10

A student observes that $$\mathrm{H_2O}$$ has a much higher surface tension than $$\mathrm{C_6H_{14}} ($$hexane). What is the best explanation for this observation?

Accepted Answer

$$\mathrm{H_2O}$$ forms hydrogen bonds, while hexane only has London dispersion forces.

Question 11

Which of the following best describes the relationship between molecular symmetry and polarity?

Accepted Answer

Symmetrical molecules are generally nonpolar because their dipoles cancel.

Question 12

Which of the following substances would you expect to be most soluble in water?

Accepted Answer

$$\mathrm{CH_3OH}$$

Question 13

Which of the following best explains why $$\mathrm{CO_2$} is a $$nonpolar molecule, even though it contains polar bonds?

Accepted Answer

The molecule is linear and symmetrical, so the bond dipoles cancel.

Question 14

Which of the following molecules can exhibit dipole-dipole interactions but not hydrogen bonding?

Accepted Answer

$$\mathrm{CH_3Cl}$$

Question 15

Which of the following is the strongest type of intermolecular force?

Accepted Answer

Ionic bonding

Question 16

Which of the following best explains why $$\mathrm{NaCl}$$ dissolves in water?

Accepted Answer

The positive and negative ions in $$\mathrm{NaCl}$$ are attracted to the partial charges on water molecules.

Question 17

Which of the following molecules would have only London dispersion forces as its intermolecular force?

Accepted Answer

$$\mathrm{CH_4$}$$

Question 18

Which of the following best describes the trend in boiling points as the strength of intermolecular forces increases?

Accepted Answer

Boiling point increases as intermolecular forces become stronger.

Question 19

Which of the following is a real-life application of hydrogen bonding?

Accepted Answer

DNA base pairing in the double helix structure

Question 20

Which of the following best explains why $$\mathrm{H_2O} is a $$polar molecule?

Accepted Answer

It has a bent shape and polar O-H bonds, resulting in a net dipole moment.

Study Guide: Properties Affected by Intermolecular Forces (IMF)

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