Question 1

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

Accepted Answer

High surface tension due to hydrogen bonding

Question 2

A scientist wants to dissolve table salt (NaCl) in water. Which property of water makes this possible?

Accepted Answer

Water's ability to form hydration shells around ions

Question 3

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice are more ordered, making ice less dense than liquid water

Question 4

Which equation correctly relates the concentration of hydrogen ions and hydroxide ions in pure water at 25°C?

Accepted Answer

$$[H^+][OH^-] = 10$$^{-14}$$

Question 5

A solution has a hydrogen ion concentration of $$[H^+] = 1 	imes 10$$^{-4}$$ M. What is its pH?

Accepted Answer

$$pH = 4$$

Question 6

Which of the following best explains why coastal regions tend to have milder climates than inland regions?

Accepted Answer

Water has a high specific heat, minimizing temperature fluctuations

Question 7

A student mixes 2 moles of glucose ($$C_6H_{12}O_6$) into enough water to make 1 liter of solution. What is the molarity (M$) of glucose in the solution?

Accepted Answer

$$2\ M$$

Question 8

Which of the following is an example of adhesion?

Accepted Answer

Water molecules forming hydrogen bonds with plant cell walls

Question 9

During ocean acidification, which chemical reaction occurs as $$CO_2$$ dissolves in seawater?

Accepted Answer

$$CO_2 + H_2O$$ \rightarrow H_2CO_3$$

Question 10

Which statement best describes a buffer?

Accepted Answer

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

Question 11

If the temperature of 1 g of water increases by 1°C, how much energy (in calories) has been absorbed?

Accepted Answer

$$1\ 	ext{cal}$$

Question 12

Which of the following substances is most likely to be hydrophobic?

Accepted Answer

Olive oil

Question 13

A solution has a pH of 9. Which of the following statements is true?

Accepted Answer

The solution is basic

Question 14

Which process explains why sweating cools the human body?

Accepted Answer

Evaporative cooling, where water absorbs heat as hydrogen bonds break

Question 15

How many joules are equivalent to 1 calorie?

Accepted Answer

$$4.184\ 	ext{J}$$

Question 16

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

Accepted Answer

Cohesion is the attraction between water molecules; adhesion is the attraction between water and other substances

Question 17

A biologist needs to prepare 0.5 L of a 1 M NaCl solution. How many moles of NaCl are required?

Accepted Answer

$$0.5\ 	ext{mol}$$

Question 18

Which of the following is a consequence of ocean acidification?

Accepted Answer

Decrease in carbonate ion concentration, hindering calcification in marine organisms

Question 19

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

Accepted Answer

Water forms hydration shells around ions due to its polarity

Question 20

A solution contains $$[OH^-] = 1 	imes 10$$^{-6}$$ M. What is the pH of the solution?

Accepted Answer

$$pH = 8$$

Water & Life: Properties and Biological Importance of Water

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