$$6.02 \times 10$$^{23}$$ particles

Question 1

Which property of water allows a water strider to walk on the surface of a pond without sinking?

Accepted Answer

Cohesion

Question 2

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

Accepted Answer

Ice is less dense than liquid water, so it floats and insulates the water below, allowing aquatic organisms to survive

Question 3

A solution has a pH of 4. Which of the following best describes this solution?

Accepted Answer

It is an acid with a high concentration of H$$^+$$ ions

Question 4

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

Accepted Answer

Hydrogen bonds must absorb or release a lot of heat before water's temperature changes

Question 5

What is the primary function of a buffer in a biological system?

Accepted Answer

To minimize changes in pH by accepting or donating H$$^+$$ ions as needed

Question 6

Which of the following best describes why sweating cools the body?

Accepted Answer

As the highest-energy water molecules evaporate, the remaining liquid is left cooler

Question 7

A nonpolar molecule that does not mix well with water is described as:

Accepted Answer

Hydrophobic

Question 8

Which of the following is the correct definition of a mole (mol) in chemistry?

Accepted Answer

$$6.02 	imes 10$$^{23}$$ particles

Question 9

Why is water considered the 'universal solvent'?

Accepted Answer

It is polar and can dissolve many ionic and polar substances

Question 10

Which of the following best describes the interaction between water molecules that leads to surface tension?

Accepted Answer

Hydrogen bonds

Question 11

A scientist dissolves table salt (NaCl) in water. What term describes the water in this solution?

Accepted Answer

Solvent

Question 12

Which property of water is most directly responsible for the movement of water from roots to leaves in tall trees?

Accepted Answer

Cohesion and adhesion

Question 13

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

Accepted Answer

Oil molecules are nonpolar and hydrophobic

Question 14

If a solution has a pH of 9, which of the following statements is true?

Accepted Answer

The solution is basic and has more OH$$^-$$ ions than H$$^+$$ ions

Question 15

Which of the following best describes the role of surfactant in the lungs of newborns?

Accepted Answer

It reduces surface tension, preventing alveoli from collapsing

Question 16

Which of the following is an example of water's high heat of vaporization being important in a real-life scenario?

Accepted Answer

Sweating cools the body as water evaporates from the skin

Question 17

Which of the following best describes the difference between cohesion and adhesion?

Accepted Answer

Cohesion is water molecules sticking to each other; adhesion is water molecules sticking to other substances

Question 18

Which of the following equations correctly represents the relationship between calories and joules?

Accepted Answer

$$1 	ext{ calorie} = 4.184 	ext{ joules}$$

Question 19

Which of the following best explains why water is essential for life as we know it?

Accepted Answer

Water's unique properties, such as cohesion, adhesion, high specific heat, and being a universal solvent, support life processes

Question 20

Which of the following best describes what happens when an acid is added to water?

Accepted Answer

The concentration of H$$^+$$ ions increases, lowering the pH

Water and Life: Properties, Functions, and Biological Importance

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