Question 1

Which property of water allows a water strider (an insect) to walk on the surface of a pond without sinking?

Accepted Answer

Cohesion due to hydrogen bonding

Question 2

Why does ice float on liquid water, and why is this important for aquatic life in winter?

Accepted Answer

Stable hydrogen bonds in ice keep water molecules farther apart, making ice less dense than liquid water.

Question 3

A beaker contains 100 mL of water at 25°C. If you add 10 g of NaCl and stir until it dissolves, what role does water play in this scenario?

Accepted Answer

Water is the solvent.

Question 4

Which of the following best explains why sweating cools the human body?

Accepted Answer

Water has a high heat of vaporization, so evaporation of sweat removes heat from the body.

Question 5

Which of the following statements about the pH scale is correct?

Accepted Answer

A solution with pH 9 is basic and has a higher concentration of $$ \mathrm{OH^-} $$ ions than $$ \mathrm{H^+} $$ ions.

Question 6

A buffer solution is added to a beaker of pure water. Then, a small amount of hydrochloric acid (HCl) is added. What will happen to the pH of the solution?

Accepted Answer

The pH will remain relatively constant due to the buffer.

Question 7

Which of the following best describes the interaction between water molecules that gives rise to surface tension?

Accepted Answer

Hydrogen bonds between adjacent water molecules.

Question 8

A student mixes oil and water in a beaker and observes that the oil forms a separate layer on top. Which property of water explains this observation?

Accepted Answer

Water is polar and oil is nonpolar, so oil is hydrophobic and does not dissolve in water.

Question 9

Which of the following equations correctly represents the dissociation of sodium hydroxide (NaOH) in water, and what effect does this have on pH?

Accepted Answer

$$ \mathrm{NaOH \rightarrow Na^+ + OH^-} $$; increases pH

Question 10

Which of the following is NOT an emergent property of water that is essential for life?

Accepted Answer

High density of ice compared to liquid water

Question 11

A solution has a pH of 2. What is the concentration of hydrogen ions $$ \left( [\mathrm{H^+}] \right)  in $$this solution?

Accepted Answer

$$ 1 	imes 10$$^{-2}$$  M$$

Question 12

Which of the following best explains why water has a high specific heat?

Accepted Answer

Hydrogen bonds between water molecules require a large amount of energy to break.

Question 13

Which of the following best describes a buffer’s function in blood?

Accepted Answer

It maintains a constant pH by both donating and accepting $$ \mathrm{H^+} $$ ions as needed.

Question 14

Which of the following statements about acids and bases is correct?

Accepted Answer

Bases decrease the concentration of $$ \mathrm{H^+} $$ ions in solution.

Question 15

A student adds a strong acid to a neutral solution, causing the pH to drop from 7 to 3. By what factor did the $$ \mathrm{[H^+]} $$ concentration increase?

Accepted Answer

By a factor of 10,000

Question 16

Which of the following best describes the difference between a homogeneous and a heterogeneous solution?

Accepted Answer

Homogeneous solutions are evenly mixed, while heterogeneous solutions are unevenly mixed.

Question 17

Which of the following molecules would be most likely to dissolve in water?

Accepted Answer

A polar molecule such as glucose

Question 18

Which of the following best explains why lakes do not freeze solid in winter, allowing aquatic life to survive?

Accepted Answer

Ice is less dense than liquid water and floats, insulating the water below.

Question 19

Which of the following is a correct statement about the relationship between temperature and kinetic energy in water molecules?

Accepted Answer

As temperature increases, the average kinetic energy of water molecules increases.

Question 20

Which of the following best describes the role of hydrogen bonding in the properties of water?

Accepted Answer

Hydrogen bonding is responsible for water’s high specific heat, cohesion, and lower density of ice.

Properties of Water: Structure, Behavior, and Importance in Chemistry

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