Question 1

Which of the following best explains why water has a much higher boiling point than hydrogen sulfide (H2S), even though both are group 6A hydrides?

Accepted Answer

Water molecules form hydrogen bonds, which are much stronger than the dipole-dipole and London dispersion forces present in H2S.

Question 2

Which of the following molecules can form hydrogen bonds with itself in the pure liquid state?

Accepted Answer

CH3NH2

Question 3

What is the primary intermolecular force responsible for the solubility of NaCl in water?

Accepted Answer

Ion-dipole forces

Question 4

Which of the following statements about hydrogen bonding is TRUE?

Accepted Answer

Hydrogen bonding occurs only when hydrogen is bonded to F, O, or N.

Question 5

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonding in ice creates an open structure, making it less dense than liquid water.

Question 6

Which of the following best describes the effect of increasing temperature on the viscosity of a liquid?

Accepted Answer

Viscosity decreases because molecules move faster and overcome intermolecular forces more easily.

Question 7

Which of the following substances would you expect to have the highest surface tension at room temperature?

Accepted Answer

Water (H2O)

Question 8

A sample of n-octane (C8H18) has a higher viscosity than a sample of n-pentane (C5H12) at the same temperature. What is the best explanation for this observation?

Accepted Answer

n-Octane has a higher molar mass, leading to stronger London dispersion forces.

Question 9

Which of the following best explains why formaldehyde (CH2O) has a higher boiling point than ethane (C2H6), even though their molar masses are nearly identical?

Accepted Answer

Formaldehyde exhibits dipole-dipole interactions, while ethane does not.

Question 10

Which of the following is NOT a requirement for hydrogen bonding to occur between molecules?

Accepted Answer

The molecule must have a large molar mass.

Question 11

Which of the following best describes the difference between cohesive and adhesive forces in the context of capillary action?

Accepted Answer

Cohesive forces are attractions between molecules of the same substance, while adhesive forces are attractions between molecules of a substance and a surface.

Question 12

Which of the following molecules would you expect to have the lowest boiling point?

Accepted Answer

H2S

Question 13

Which of the following is the strongest type of intermolecular force present in a mixture of NaCl dissolved in water?

Accepted Answer

Ion-dipole forces

Question 14

Which of the following best explains why DNA strands are held together?

Accepted Answer

Hydrogen bonds between complementary bases

Question 15

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

Accepted Answer

LDFs increase with increasing molecular weight.

Question 16

Which of the following best describes the trend in viscosity for a series of hydrocarbons as their molar mass increases?

Accepted Answer

Viscosity increases because London dispersion forces become stronger.

Question 17

Which of the following is a correct statement about the effect of temperature on surface tension?

Accepted Answer

Surface tension decreases as temperature increases because the average kinetic energy of molecules increases.

Question 18

Which of the following molecules exhibits only London dispersion forces as its primary intermolecular force?

Accepted Answer

I2

Question 19

Which of the following best explains why mercury forms a convex meniscus in a glass tube, while water forms a concave meniscus?

Accepted Answer

Water has stronger adhesive forces to glass than cohesive forces, while mercury has stronger cohesive forces than adhesive forces.

Chap 12 lecture 3 study guide chem 136

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