Question 1

Which property of water allows it to moderate Earth's climate and maintain relatively stable temperatures in coastal regions?

Accepted Answer

Its high specific heat capacity

Question 2

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

Accepted Answer

Ice is less dense than liquid water due to hydrogen bonds holding water molecules further apart, allowing it to float and insulate the water below.

Question 3

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

Accepted Answer

$$pH = 5$$

Question 4

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

Accepted Answer

Water molecules are polar, allowing them to form hydration shells around ions and separate them.

Question 5

If you add 0.01 mol of a strong acid to pure water, the pH drops from 7 to 2. If you add the same amount to blood, the pH drops from 7.4 to 7.3. What property of blood explains this difference?

Accepted Answer

Blood contains buffers that minimize changes in pH.

Question 6

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

Accepted Answer

Acids increase the concentration of $$H^+$$ ions, lowering the pH; bases decrease $$H^+ or $$increase $$OH^-$$, raising the pH.

Question 7

A beaker contains a solution with a pH of 3. How many times greater is the concentration of $$H^+$$ ions compared to a solution with a pH of 6?

Accepted Answer

1000 times greater

Question 8

Which of the following scenarios best illustrates the concept of cohesion in water?

Accepted Answer

A water strider insect walking on the surface of a pond due to surface tension

Question 9

What is the primary reason that water has a high surface tension compared to most other liquids?

Accepted Answer

Hydrogen bonds between water molecules create a strong attraction at the surface.

Question 10

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

Accepted Answer

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

Question 11

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

Accepted Answer

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

Question 12

A protein is placed in water and unfolds (denatures). Which property of water is most responsible for this effect?

Accepted Answer

Water's ability to form hydrogen bonds with polar and charged groups on the protein

Question 13

If the pH of a solution changes from 8 to 6, what happens to the $$H^+$$ concentration?

Accepted Answer

It increases by 100 times

Question 14

Which of the following best explains why sweating cools the human body?

Accepted Answer

Evaporation of sweat removes heat as the molecules with the highest kinetic energy leave the skin.

Question 15

Which of the following is an example of adhesion?

Accepted Answer

Water molecules sticking to the walls of plant vessels, helping water move upward against gravity

Question 16

Which equation correctly represents the relationship between pH and hydrogen ion concentration?

Accepted Answer

$$pH = -\log [H^+]$$

Question 17

Ocean acidification is primarily caused by which of the following processes?

Accepted Answer

Increased uptake of $$CO_2 by $$the ocean, forming carbonic acid and increasing $$H^+$$ concentration

Question 18

Which of the following best describes a hydrophobic substance?

Accepted Answer

A substance that is nonpolar and does not interact with water

Question 19

Which of the following is a direct consequence of water's polarity?

Accepted Answer

Water can dissolve ionic and polar substances.

Question 20

A patient is experiencing acidosis, with a blood pH of 7.2. Which buffer system in the blood helps to restore normal pH?

Accepted Answer

The carbonic acid-bicarbonate buffer system

Water and Life: Properties, Hydrogen Bonding, and pH in Biology

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