Question 1

Which of the following statements best explains why ice floats on water?

Accepted Answer

Ice is less dense than water due to the formation of cavities from hydrogen bonding.

Question 2

Which intermolecular force is present in ALL substances, regardless of their polarity?

Accepted Answer

Dispersion forces

Question 3

A sample of liquid ethanol is placed in a closed container. Over time, the pressure inside the container increases and then levels off. What is the term for the pressure at which evaporation and condensation occur at equal rates?

Accepted Answer

Vapor pressure

Question 4

Which of the following molecules would exhibit the strongest hydrogen bonding?

Accepted Answer

HF

Question 5

Why does n-pentane (C5H12) have a higher boiling point than neopentane (C5H12)?

Accepted Answer

n-Pentane has a larger surface area, increasing dispersion forces.

Question 6

Which process is represented by the equation $$	ext{Solid} ightarrow 	ext{Gas}$$ and is endothermic?

Accepted Answer

Sublimation

Question 7

Which of the following substances would have the highest boiling point, based on the strength of intermolecular forces?

Accepted Answer

BaCl2

Question 8

What is the main reason that water (H2O) has a much higher boiling point than methane (CH4)?

Accepted Answer

Water has stronger hydrogen bonding.

Question 9

Which intermolecular force is responsible for the solubility of ionic compounds in water?

Accepted Answer

Ion-dipole forces

Question 10

At higher altitudes, water boils at a temperature lower than 100°C. Which statement best explains this phenomenon?

Accepted Answer

The vapor pressure of water equals the lower atmospheric pressure at higher altitudes.

Question 11

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

Accepted Answer

Increasing the temperature

Question 12

Which of the following molecules would have the lowest boiling point?

Accepted Answer

Ne

Question 13

Which of the following statements about dispersion forces is TRUE?

Accepted Answer

Dispersion forces increase with increasing molecular weight.

Question 14

Which of the following phase changes is exothermic?

Accepted Answer

Condensation

Question 15

A phase diagram shows the triple point of a substance. What does the triple point represent?

Accepted Answer

The temperature and pressure at which solid, liquid, and gas phases coexist in equilibrium.

Question 16

Which of the following best describes the relationship between molecular shape and dispersion forces?

Accepted Answer

Linear molecules have stronger dispersion forces due to larger surface area.

Question 17

Which of the following is NOT a type of intermolecular force?

Accepted Answer

Covalent bonding

Question 18

Which of the following statements about the boiling points of covalent hydrides is correct?

Accepted Answer

Hydrides with hydrogen bonding have unusually high boiling points.

Question 19

Which of the following molecules would have both dispersion and dipole-dipole forces, but NOT hydrogen bonding?

Accepted Answer

CH3CN

Question 20

A gas is liquefied at its critical temperature and pressure. Which equation best represents the relationship between critical temperature ($$T_c) $$and critical pressure ($$P_c$$)?

Accepted Answer

$$P_c is $$the pressure required to liquefy a gas at $$T_c.$$

Chemistry Chatper 11

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