Question 1

Which of the following best describes the difference between intermolecular and intramolecular forces?

Accepted Answer

Intramolecular forces are chemical bonds within a molecule, while intermolecular forces are attractions between separate molecules.

Question 2

Which of the following substances would you expect to have the highest boiling point based on London dispersion forces alone?

Accepted Answer

CI4

Question 3

Why does Br2 exist as a liquid at room temperature while Cl2 is a gas and I2 is a solid?

Accepted Answer

Br2 has stronger London dispersion forces than Cl2 but weaker than I2 due to its intermediate molar mass.

Question 4

Which factor does NOT increase the strength of London dispersion forces?

Accepted Answer

Increasing electronegativity difference

Question 5

Which of the following best explains why n-pentane has a higher boiling point than neopentane, even though they have the same molecular formula?

Accepted Answer

n-pentane has a larger surface area for intermolecular contact, resulting in stronger London dispersion forces.

Question 6

Which of the following statements about London dispersion forces is FALSE?

Accepted Answer

They are caused by differences in electronegativity between atoms.

Question 7

Which noble gas has the highest boiling point, and why?

Accepted Answer

Xe, because it has the largest molar mass and most electrons, leading to the strongest London dispersion forces.

Question 8

Which of the following best describes the role of hydrogen bonds in the structure of DNA?

Accepted Answer

Hydrogen bonds connect the two strands of DNA by pairing the nitrogenous bases.

Question 9

A sample of a noble gas is cooled from room temperature to 4 K. Which property is most responsible for the gas condensing into a liquid?

Accepted Answer

London dispersion forces

Question 10

Which equation describes the relationship between vapor pressure and temperature for a liquid, and what does it allow you to calculate?

Accepted Answer

$\ln P = -\frac{\Delta H_{vap}}{R} \left( \frac{1}{T} \right) + C$; it allows you to calculate the enthalpy of vaporization from vapor pressure data.

Question 11

Which of the following molecules would have the weakest London dispersion forces?

Accepted Answer

F2

Question 12

Which of the following is a real-life consequence of strong intermolecular forces in a liquid?

Accepted Answer

The liquid will have high surface tension and viscosity.

Question 13

Which of the following best explains why the boiling point of n-nonane ($C_9H_{20}$) is higher than that of n-pentane ($C_5H_{12}$)?

Accepted Answer

n-nonane has a higher molar mass and more electrons, resulting in stronger London dispersion forces.

Question 14

Which of the following statements about phase changes is correct?

Accepted Answer

During melting, intermolecular forces are overcome, but molecules remain intact.

Question 15

Which of the following best explains why larger atoms are more polarizable?

Accepted Answer

They have more electrons that are farther from the nucleus, making the electron cloud easier to distort.

Question 16

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

Accepted Answer

Covalent bonding

Question 17

Which of the following best describes why the boiling points of noble gases increase down the group?

Accepted Answer

The number of electrons increases, enhancing London dispersion forces.

Question 18

Which of the following is the best explanation for why a branched alkane has a lower boiling point than its straight-chain isomer?

Accepted Answer

Branched alkanes have less surface area for intermolecular contact, resulting in weaker London dispersion forces.

Question 19

Which of the following is a correct statement about the effect of intermolecular forces on the physical properties of substances?

Accepted Answer

Stronger intermolecular forces result in higher surface tension and lower vapor pressure.

Solids, Liquids, and Intermolecular Forces: Study Guide

Study Guide - Practice Questions