Question 1

Which of the following intermolecular forces is the strongest?

Accepted Answer

Ionic attraction

Question 2

What is the main reason water (H$_2$O) has a much higher boiling point than H$_2$S, H$_2$Se, and H$_2$Te, despite its lower molar mass?

Accepted Answer

Water molecules form hydrogen bonds.

Question 3

Which of the following molecules will exhibit only London dispersion forces as its strongest intermolecular force?

Accepted Answer

CO$_2$

Question 4

A solution of NaCl in water is stabilized primarily by which type of intermolecular force?

Accepted Answer

Ion-dipole interactions

Question 5

Which of the following statements best explains why honey is more viscous than water?

Accepted Answer

Honey contains more hydrogen bonds between molecules.

Question 6

Which of the following will increase the vapor pressure of a liquid?

Accepted Answer

Decreasing the strength of intermolecular forces

Question 7

Which equation relates the vapor pressure and temperature of a liquid?

Accepted Answer

$\ln P = -\frac{\Delta H_{vap}}{R}\frac{1}{T} + b$

Question 8

A liquid has a vapor pressure of 150 mmHg at 300 K and 300 mmHg at 320 K. What is the enthalpy of vaporization ($\Delta H_{vap}$) in kJ/mol? Use $R = 8.314$ J/(mol·K).

Accepted Answer

$\Delta H_{vap} = 34.6$ kJ/mol

Question 9

Which of the following best describes the process of evaporation?

Accepted Answer

Molecules at the surface of a liquid gain enough kinetic energy to break free from intermolecular attractions and escape into the gas phase.

Question 10

Which of the following molecules will have the highest boiling point?

Accepted Answer

C$_5$H$_{12}$ (n-pentane)

Question 11

Which of the following is true about surface tension?

Accepted Answer

It is the energy required to increase the surface area of a liquid by a unit area.

Question 12

Which of the following is NOT a consequence of molecular polarity?

Accepted Answer

Lower melting point

Question 13

Which of the following is required for hydrogen bonding to occur?

Accepted Answer

A hydrogen atom bonded to N, O, or F

Question 14

Which of the following best explains why oil and water do not mix?

Accepted Answer

Oil is nonpolar and water is polar.

Question 15

Which of the following statements about phase diagrams is correct?

Accepted Answer

The critical point is the temperature above which the liquid state does not exist.

Question 16

Which of the following equations is used to calculate the heat required for a phase change?

Accepted Answer

$q = n\Delta H$

Question 17

A crystalline solid differs from an amorphous solid in that:

Accepted Answer

A crystalline solid has a well-defined ordered structure in three dimensions.

Question 18

Which of the following is the correct empirical formula for a unit cell containing 4 atoms of element A and 4 atoms of element B?

Accepted Answer

AB

Question 19

Which of the following statements about boiling point and external pressure is correct?

Accepted Answer

The boiling point decreases as external pressure decreases.

Liquids and Solids: Intermolecular Forces, Physical Properties, and Phase Changes

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