Question 1

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

Accepted Answer

Cohesion resulting in high surface tension

Question 2

Why does ice float on liquid water, and why is this property crucial for aquatic life in cold climates?

Accepted Answer

Hydrogen bonds in ice are more stable and keep molecules farther apart, making ice less dense than liquid water.

Question 3

A scientist dissolves 58.44 g of NaCl (molecular mass = 58.44 g/mol) in enough water to make 1 L of solution. What is the molarity (M) of the solution?

Accepted Answer

$$1\ \mathrm{M}$$

Question 4

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 5

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

Accepted Answer

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

Question 6

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

Accepted Answer

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

Question 7

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

Accepted Answer

A buffer is a substance that minimizes changes in $$[H^+]$$ and $$[OH^-] in a $$solution.

Question 8

Which of the following is an example of water’s versatility as a solvent in a biological context?

Accepted Answer

Water dissolves ionic compounds like NaCl and polar molecules such as sugars.

Question 9

If the concentration of $$[OH^-] in a $$solution is $$1 	imes 10$$^{-10}$$\ \mathrm{M}$$, what is the pH of the solution at 25°C?

Accepted Answer

$$pH = 4$$

Question 10

Which property of water explains why sweating cools the human body?

Accepted Answer

Evaporative cooling due to water’s high heat of vaporization

Question 11

A hydrophobic molecule is most likely to be found in which part of a cell?

Accepted Answer

Embedded in the cell membrane

Question 12

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

Accepted Answer

Temperature is the average kinetic energy of the molecules in a body of matter.

Question 13

A plant transports water from its roots to its leaves. Which combination of water’s properties is most directly responsible for this process?

Accepted Answer

Cohesion and adhesion

Question 14

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

Accepted Answer

A base increases the $$[OH^-] in a $$solution.

Question 15

A solution has a pH of 8. Which of the following statements is true?

Accepted Answer

The solution is basic.

Question 16

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

Accepted Answer

Oil molecules are nonpolar and hydrophobic.

Question 17

If you add a strong acid to pure water, what happens to the $$[H^+]$$ and pH?

Accepted Answer

$$[H^+]$$ increases and pH decreases

Question 18

Which of the following is the correct formula for calculating pH?

Accepted Answer

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

Question 19

A buffer solution contains a weak acid and its conjugate base. What happens when a small amount of strong acid is added to this buffer?

Accepted Answer

The buffer neutralizes the added acid, minimizing the change in pH.

Question 20

Which of the following best describes the role of water in the chemical reactions of living organisms?

Accepted Answer

Water acts as a solvent, allowing reactants to collide and react.

Water and Life: Properties, Functions, and Biological Importance

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