Question 1

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

Accepted Answer

Cohesion resulting in high surface tension

Question 2

Why does ice float on liquid water, and what is the biological significance of this phenomenon?

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds keep water molecules farther apart in the solid state, insulating aquatic environments.

Question 3

A scientist adds a strong acid to a solution, causing the pH to drop from 7 to 3. By what factor did the hydrogen ion concentration increase?

Accepted Answer

$$10^4$$

Question 4

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

Accepted Answer

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

Question 5

A plant is able to transport water from its roots to its leaves against gravity. Which combination of water's properties is primarily responsible for this process?

Accepted Answer

Cohesion and adhesion

Question 6

Which of the following equations correctly represents the dissociation of water molecules?

Accepted Answer

$$H_2O \rightarrow H^+ + OH^-$$

Question 7

A solution has a pH of 5. What is the concentration of hydrogen ions ($$[H^+]) in $$this solution?

Accepted Answer

$$[H^+] = 10$$^{-5}$$\,M$$

Question 8

Which of the following best describes a buffer’s role in biological systems?

Accepted Answer

Buffers maintain pH by accepting or donating $$H^+$$ ions as needed.

Question 9

A protein requires a specific pH to function properly. What should be added to the solution to maintain this pH during an experiment?

Accepted Answer

A buffer

Question 10

Which of the following is a direct result of water’s polarity?

Accepted Answer

Water can dissolve ionic and polar substances.

Question 11

A lake has a pH of 4.0. What is the concentration of hydroxide ions ($$[OH^-]) in $$the lake?

Accepted Answer

$$[OH^-] = 10$$^{-10}$$\,M$$

Question 12

Which of the following substances is hydrophobic?

Accepted Answer

Olive oil

Question 13

If the pH of a solution changes from 8 to 6, how does the hydrogen ion concentration change?

Accepted Answer

It increases by a factor of 100

Question 14

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 heat of evaporation

Question 15

What type of bond is responsible for the cohesion between water molecules?

Accepted Answer

Hydrogen bond

Question 16

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

Accepted Answer

Acids increase $$[H^+]$$ and lower pH; bases decrease $$[H^+]$$ and raise pH.

Question 17

Which of the following acts as a buffer in human blood?

Accepted Answer

Both carbonic acid and bicarbonate ion

Question 18

A solution has a pH of 10. What is the concentration of hydroxide ions ($$[OH^-]) in $$this solution?

Accepted Answer

$$[OH^-] = 10$$^{-4}$$\,M$$

Question 19

Which of the following best explains why salt (NaCl) dissolves easily in water?

Accepted Answer

The partial positive charge of water's hydrogen atoms attracts Cl$$^-$$ ions, and the partial negative charge of water's oxygen atoms attracts Na$$^+$$ ions.

Question 20

Which of the following is true about the pH scale?

Accepted Answer

A solution with pH 7 is neutral because $$[H^+] = [OH^-]$$

Chapter 3: Water and Life – Properties, Structure, and Biological Importance

Study Guide - Practice Questions

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