$$[H^+] = 1 \times 10$$^{-4}$$ \ \mathrm{M}$$

Question 1

Which property of water is primarily responsible for the ability of some insects to walk on water surfaces?

Accepted Answer

High surface tension due to cohesion

Question 2

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice keep water molecules farther apart, making it less dense

Question 3

Which of the following best explains why coastal areas tend to have milder climates than inland areas?

Accepted Answer

Water’s high specific heat allows it to absorb and release large amounts of heat with little temperature change

Question 4

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ \ \mathrm{M}$$

Question 5

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

Accepted Answer

Sweating during exercise, which cools the body as sweat evaporates

Question 6

What is the primary reason water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water molecules form hydration shells around ions due to their polarity

Question 7

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

Accepted Answer

A base reduces the $$[H^+]$$ concentration in a solution

Question 8

A buffer solution contains a weak acid and its corresponding base. What is the main function of this buffer in biological systems?

Accepted Answer

To minimize changes in $$[H^+]$$ and maintain a stable pH

Question 9

Which of the following best describes why oil does not dissolve in water?

Accepted Answer

Oil molecules are nonpolar and do not interact favorably with polar water molecules

Question 10

If the pH of a solution changes from 6 to 4, how does the hydrogen ion concentration change?

Accepted Answer

It increases by a factor of 100

Question 11

Which property of water is most important for the movement of water from roots to leaves in plants?

Accepted Answer

Cohesion and adhesion

Question 12

What is the effect of ocean acidification caused by increased atmospheric $$CO_2$$?

Accepted Answer

It forms carbonic acid, lowering the pH and threatening marine life

Question 13

Which of the following best describes the relationship between temperature and kinetic energy?

Accepted Answer

Temperature is the average kinetic energy of the molecules

Question 14

A solution contains $$[OH^-] = 1 	imes 10$$^{-6}$$ \ \mathrm{M}. $$What is the pH of this solution?

Accepted Answer

$$pH = 8$$

Question 15

Which of the following is a direct consequence of water’s high heat of vaporization for living organisms?

Accepted Answer

Evaporative cooling helps prevent overheating

Question 16

Which of the following best explains why water is considered a polar molecule?

Accepted Answer

The electrons spend more time near the oxygen atom, creating a partial negative charge

Question 17

Which of the following is NOT one of the four emergent properties of water that contribute to Earth’s suitability for life?

Accepted Answer

High density of ice

Question 18

Which of the following best describes the role of hydrogen bonds in water’s high specific heat?

Accepted Answer

Heat is absorbed to break hydrogen bonds and released when they form, requiring more energy to change temperature

Question 19

A hydrophilic substance is best described as:

Accepted Answer

A substance that has an affinity for water

Question 20

Which of the following best explains why even a slight change in pH can be harmful to living cells?

Accepted Answer

Changes in $$[H^+]$$ and $$[OH^-]$$ can drastically affect the chemistry of a cell

Water and Life: Properties and Biological Importance

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