Question 1

Which property of water allows some insects, such as water striders, to walk on the surface of water without sinking?

Accepted Answer

Cohesion due to hydrogen bonding

Question 2

A solution has a pH of 4. How many times greater is the hydrogen ion concentration compared to a solution with a pH of 7?

Accepted Answer

$$1,000$$ times greater

Question 3

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

Accepted Answer

Hydrogen bonds between water molecules require significant energy to break.

Question 4

What is the correct chemical equation for the dissociation of acetic acid (a weak acid) in water?

Accepted Answer

$$\mathrm{CH_3COOH} \rightarrow \mathrm{CH_3COO^-} + \mathrm{H^+}$$

Question 5

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

Accepted Answer

Acids decrease the pH of a solution by increasing $$\mathrm{H^+}$$ concentration.

Question 6

Which of the following best describes a buffer system in biological fluids?

Accepted Answer

A buffer system maintains pH by releasing or absorbing $$\mathrm{H^+}$$ ions as needed.

Question 7

Which of the following molecules is most likely to be hydrophilic?

Accepted Answer

A molecule with many oxygen and nitrogen atoms

Question 8

What happens to the pH of a solution if the concentration of hydrogen ions ($$\mathrm{[H^+]}) $$increases from $$1 	imes 10$$^{-7}$$ M to 1$$ 	imes $$10^{-5} M$$?

Accepted Answer

The pH decreases by 2 units

Question 9

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

Accepted Answer

The negative end of water molecules surrounds sodium ions, and the positive end surrounds chloride ions.

Question 10

Which of the following is an example of a strong base?

Accepted Answer

Sodium hydroxide ($$\mathrm{NaOH})$$

Question 11

A protein has both hydrophilic and hydrophobic regions. Which of the following best describes how this affects its interaction with water?

Accepted Answer

The hydrophilic regions interact with water, while the hydrophobic regions avoid water.

Question 12

Which of the following best describes the adhesion property of water?

Accepted Answer

Water molecules stick to other types of polar molecules or surfaces.

Question 13

If a solution is described as neutral, what is the relationship between the concentrations of hydrogen ions ($$\mathrm{[H^+]}) $$and hydroxide ions ($$\mathrm{[OH^-]}$$)?

Accepted Answer

$$\mathrm{[H^+]}$$ equals $$\mathrm{[OH^-]}$$

Question 14

Which of the following best explains why sweating helps cool the human body?

Accepted Answer

Evaporation of sweat removes heat due to water's high heat of vaporization.

Question 15

Which of the following is a correct statement about the pH scale?

Accepted Answer

A solution with pH 5 has 100 times more hydrogen ions than a solution with pH 7.

Question 16

Which of the following best describes the molecular structure of water?

Accepted Answer

Water is a polar molecule with partial negative charge near the oxygen atom and partial positive charges near the hydrogen atoms.

Question 17

Which of the following is an example of a weak base?

Accepted Answer

Ammonia ($$\mathrm{NH_3$})$$

Question 18

Which of the following best explains why ice floats on liquid water?

Accepted Answer

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

Question 19

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers minimize changes in pH by absorbing or releasing hydrogen ions.

Water, Acids, Bases, and Solutions in Biology

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