AP - Advanced Placement Intermolecular Forces and Properties 1

Question 1

Which of the following noble gases has the highest boiling point?

Accepted Answer

Xe

Answer

He

Answer

Ne

Answer

Ar

Question 2

Which of the following molecules is capable of forming hydrogen bonds with itself (intermolecular self-association)?

Accepted Answer

CH₃NH₂

Answer

CH₃OCH₃

Answer

CH₃F

Answer

CH₄

Question 3

Which of the following liquids would be expected to have the highest vapor pressure at 25°C?

Accepted Answer

Diethyl ether (C₂H₅OC₂H₅)

Answer

Water (H₂O)

Answer

Ethanol (C₂H₅OH)

Answer

Glycerol (C₃H₈O₃)

Question 4

n-Pentane (C₅H₁₂) boils at 36°C while neopentane (also C₅H₁₂) boils at only 9°C. Which explanation best accounts for this difference?

Accepted Answer

n-Pentane's elongated chain provides greater surface area for London dispersion interactions.

Answer

n-Pentane has a larger molar mass than neopentane.

Answer

n-Pentane is more polar than neopentane.

Answer

Neopentane forms stronger hydrogen bonds than n-pentane.

Question 5

Which of the following correctly ranks the three major types of intermolecular forces from weakest to strongest?

Accepted Answer

London dispersion < dipole-dipole < hydrogen bonding

Answer

Dipole-dipole < London dispersion < hydrogen bonding

Answer

Hydrogen bonding < dipole-dipole < London dispersion

Answer

London dispersion < hydrogen bonding < dipole-dipole

Question 6

Among the Group 16 hydrides, H₂S, H₂Se, and H₂Te show a regular increase in boiling point with molar mass, yet water (H₂O) has an anomalously high boiling point far above the trend. What is the primary reason for this anomaly?

Accepted Answer

Water molecules form an extensive hydrogen-bond network because oxygen is highly electronegative and small enough to concentrate charge density.

Answer

Water has the greatest molar mass among the Group 16 hydrides.

Answer

Water experiences stronger London dispersion forces than H₂Te.

Answer

Water is a linear molecule, allowing maximum molecular contact.