Question 1

Which property of water is primarily responsible for the upward movement of water in plants against gravity?

Accepted Answer

Cohesion and adhesion

Question 2

Why does ice float on liquid water?

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds keep water molecules further apart in the solid state.

Question 3

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

Accepted Answer

$$pH = 5$$

Question 4

Which of the following best explains why water is an excellent solvent for ionic compounds like NaCl?

Accepted Answer

Water molecules are polar and can form hydration shells around ions, separating them.

Question 5

What happens to the average kinetic energy (KE) of the remaining water molecules after some have evaporated from a surface?

Accepted Answer

It decreases because the fastest (highest KE) molecules have left.

Question 6

Which of the following statements about buffers is correct?

Accepted Answer

Buffers minimize changes in pH by accepting or donating H$$^+$$ ions.

Question 7

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

Accepted Answer

It increases by 100 times.

Question 8

Which of the following best describes the difference between hydrophilic and hydrophobic substances?

Accepted Answer

Hydrophilic substances are polar and interact with water; hydrophobic substances are nonpolar and do not interact with water.

Question 9

Which equation correctly relates pH and hydrogen ion concentration?

Accepted Answer

$$pH = -\log_{10}[H^+]$$

Question 10

Why does water have a higher specific heat than ethyl alcohol?

Accepted Answer

Water forms more hydrogen bonds, requiring more energy to change its temperature.

Question 11

A protein dissolves in water but does not dissociate into its atoms. What property of the protein allows this?

Accepted Answer

The protein has hydrophilic amino acids on its surface that interact with water.

Question 12

Which of the following is a real-world example of water's high heat of vaporization?

Accepted Answer

Sweating cools the human body as water evaporates from the skin.

Question 13

Which buffer system is primarily responsible for maintaining the pH of human blood?

Accepted Answer

Bicarbonate buffer system

Question 14

What is the main reason oil and water do not mix?

Accepted Answer

Oil is nonpolar and cannot form hydrogen bonds with water.

Question 15

Which of the following best explains why aquatic life can survive under ice in winter?

Accepted Answer

Ice is less dense than water and floats, insulating the water below and preventing it from freezing solid.

Question 16

Which of the following is true about the phosphate buffer system in cells?

Accepted Answer

It maintains pH by both accepting and donating H$$^+$$ ions depending on the pH.

Question 17

If a solution has a pH of 8, what is the hydrogen ion concentration?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-8}$$ M

Question 18

Which of the following best describes the role of van der Waals interactions in oil droplets?

Accepted Answer

They stabilize oil droplets by weak attractions between nonpolar molecules.

Question 19

A patient’s blood pH drops from 7.4 to 7.1. What is the physiological consequence if this change is not buffered?

Accepted Answer

Breakdown of proteins and disruption of cellular processes.

Question 20

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

Accepted Answer

Water expands and becomes less dense as it freezes, unlike most substances.

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

Study Guide - Practice Questions