Question 1

Which property of water is primarily responsible for the ability of plants to transport water from their roots to their leaves against gravity?

Accepted Answer

Cohesion between water molecules

Question 2

A scientist adds a drop of oil to a beaker of water. The oil does not mix with the water and forms a separate layer. Which property of oil explains this behavior?

Accepted Answer

Oil is hydrophobic because it contains nonpolar bonds

Question 3

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

Accepted Answer

Ice is less dense than liquid water due to stable hydrogen bonds, preventing bodies of water from freezing solid

Question 4

Which equation correctly defines the pH of a solution?

Accepted Answer

$$pH = -\log [H^+]$$

Question 5

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-5}$$ M. What is its pH?

Accepted Answer

pH = 5

Question 6

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

Accepted Answer

Hydrogen bonds between water molecules absorb heat when they break and release heat when they form

Question 7

A buffer solution is added to a beaker of pure water. Which of the following best describes the function of the buffer?

Accepted Answer

It minimizes changes in the concentrations of $$H^+$$ and $$OH^-$$ ions

Question 8

Which of the following is a direct consequence of water’s ability to form hydrogen bonds?

Accepted Answer

Water has a high surface tension

Question 9

A beaker contains 0.5 moles of NaCl dissolved in 1 liter of water. What is the molarity of the NaCl solution?

Accepted Answer

0.5 M

Question 10

Which of the following best describes why water is called the 'universal solvent'?

Accepted Answer

Water’s polarity allows it to dissolve many ionic and polar substances

Question 11

During a hot day, sweating helps cool the human body. Which property of water is most directly responsible for this cooling effect?

Accepted Answer

Water’s high heat of vaporization

Question 12

If the pH of a solution changes from 7 to 5, what happens to the hydrogen ion concentration?

Accepted Answer

It increases by 100-fold

Question 13

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

Accepted Answer

An acid increases the concentration of $$H^+ in a $$solution

Question 14

A solution at 25°C has $$[H^+] = 1 	imes 10$$^{-7}$$ M. What is the $$[OH^-]$$ in this solution?

Accepted Answer

$$1 	imes 10$$^{-7}$$ M

Question 15

Which of the following best explains why water moderates temperature so effectively?

Accepted Answer

Water can absorb or release a large amount of heat with only a slight change in its own temperature

Question 16

A scientist wants to prepare 1 liter of a 0.1 M glucose solution. The molecular mass of glucose is 180 g/mol. How many grams of glucose should be dissolved?

Accepted Answer

18 g

Question 17

Which of the following is an example of adhesion?

Accepted Answer

Water molecules sticking to plant cell walls

Question 18

Which of the following best describes a hydrophilic substance?

Accepted Answer

A substance that has an affinity for water

Question 19

Why is the internal pH of most living cells maintained close to 7?

Accepted Answer

Because buffers minimize changes in $$[H^+]$$ and $$[OH^-]$$

Question 20

Which of the following best describes the relationship between kinetic energy, thermal energy, and temperature in water?

Accepted Answer

Kinetic energy is the energy of motion, thermal energy is the total kinetic energy of molecules, and temperature measures the average kinetic energy

Water and Life: Properties and Biological Importance

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