Question 1

Which property of water allows insects such as water striders to walk on the surface of a pond without sinking?

Accepted Answer

Cohesion due to hydrogen bonding

Question 2

A scientist is studying a lake that remains liquid even when the air temperature drops below 0°C. Which property of water best explains why the lake does not freeze solid from the bottom up?

Accepted Answer

Ice is less dense than liquid water

Question 3

Which of the following best explains why sweating helps cool the human body?

Accepted Answer

Evaporation of water requires energy, which is absorbed from the skin

Question 4

A solution is made by dissolving 34.2 grams of sucrose (molar mass = 342 g/mol) in enough water to make 1 liter of solution. What is the molarity of the solution? Use the formula $$M = \frac{	ext{moles of solute}}{	ext{liters of solution}}.$$

Accepted Answer

0.1 M

Question 5

Which of the following statements about hydrogen bonds in water is correct?

Accepted Answer

Hydrogen bonds form between the hydrogen atom of one water molecule and the oxygen atom of another

Question 6

If the pH of a solution changes from 6 to 4, what happens to the concentration of hydrogen ions $$[H^+]$$?

Accepted Answer

It increases by a factor of 100

Question 7

Which property of water is most important for maintaining a stable climate in coastal cities?

Accepted Answer

Water's high specific heat

Question 8

A buffer solution contains carbonic acid ($$H_2CO_3) $$and bicarbonate ($$HCO_3$$^-$$). What is the primary function of this buffer in human blood?

Accepted Answer

To minimize changes in pH when acids or bases are added

Question 9

Which of the following best describes why water is an excellent solvent for ionic compounds?

Accepted Answer

Water molecules are polar and can form hydration shells around ions

Question 10

A plant wilts when its cells lose water. Which property of water helps plants transport water from roots to leaves against gravity?

Accepted Answer

Cohesion and adhesion

Question 11

If a solution has a hydrogen ion concentration of $$[H^+] = 1 	imes 10$$^{-7}$$ M, what is its pH? Use the formula $$	ext{pH} = -\log_{10}[H^+]$$.

Accepted Answer

pH = 7

Question 12

Which of the following scenarios best illustrates the concept of evaporative cooling?

Accepted Answer

A dog panting after running on a hot day

Question 13

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice keep water molecules farther apart

Question 14

A student adds a strong acid to a beaker of pure water, causing the pH to drop from 7 to 2. By what factor did the hydrogen ion concentration increase?

Accepted Answer

By a factor of 10,000

Question 15

Which of the following is a real-world consequence of ocean acidification caused by increased $$CO_2$$ absorption?

Accepted Answer

Decreased ability of marine organisms to form calcium carbonate shells

Question 16

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

Accepted Answer

Hydrogen bonds must be broken before the temperature can increase

Question 17

A solution has a pH of 9. Which of the following best describes this solution?

Accepted Answer

It is basic and has a low $$[H^+]$$

Question 18

Which of the following is an example of water acting as a buffer in a biological system?

Accepted Answer

Water maintaining blood pH by interacting with carbonic acid and bicarbonate

Question 19

Which of the following best describes the relationship between acids, bases, and the pH scale?

Accepted Answer

Acids increase $$[H^+]$$ and have a pH less than 7; bases decrease $$[H^+]$$ and have a pH greater than 7

Question 20

A researcher wants to prepare 0.5 L of a 0.2 M sucrose solution. How many grams of sucrose (molar mass = 342 g/mol) are needed? Use $$	ext{moles} = M 	imes L$$ and $$	ext{grams} = 	ext{moles} 	imes 	ext{molar mass}.$$

Accepted Answer

Properties of Water: The Elixir of Life

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