Question 1

Which property of water allows it to exist naturally on Earth as a solid, liquid, and gas, and why is this important for life?

Accepted Answer

Its ability to form hydrogen bonds, which allows for a wide range of temperatures where water is liquid.

Question 2

What type of chemical bond is primarily responsible for the cohesion between water molecules?

Accepted Answer

Hydrogen bond

Question 3

A plant is able to transport water from its roots to its leaves against gravity. Which two properties of water are most directly responsible for this phenomenon?

Accepted Answer

Cohesion and adhesion

Question 4

Why can a spider walk on the surface of a pond without sinking?

Accepted Answer

Because water has a high surface tension due to hydrogen bonding.

Question 5

Which property of water helps coastal cities maintain more moderate temperatures compared to inland cities?

Accepted Answer

Water's high specific heat capacity

Question 6

Sweating cools the human body because:

Accepted Answer

Water absorbs heat as it evaporates, removing energy from the body.

Question 7

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

Accepted Answer

Ice is less dense than liquid water due to stable hydrogen bonds, insulating water below and allowing life to survive in winter.

Question 8

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

Accepted Answer

Water is a polar molecule, so its partial charges surround and separate Na+ and Cl– ions.

Question 9

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

Accepted Answer

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

Question 10

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

Accepted Answer

Acids increase the concentration of $$H^+$$ ions in solution.

Question 11

What is the main threat to marine life caused by ocean acidification?

Accepted Answer

Reduction in calcium carbonate availability, which affects shell formation in marine species.

Question 12

Which equation correctly represents the formation of carbonic acid in ocean acidification?

Accepted Answer

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

Question 13

A buffer solution is important in biological systems because it:

Accepted Answer

Minimizes changes in $$[H^+]$$ concentration, maintaining a stable pH.

Question 14

Which of the following best describes a hydrophilic substance?

Accepted Answer

A polar substance that dissolves in water.

Question 15

If the pH of a solution changes from 7 to 5, how does the hydrogen ion concentration change?

Accepted Answer

It increases by 100 times.

Question 16

Which of the following is NOT a life-supporting property of water?

Accepted Answer

Water's ability to conduct electricity.

Question 17

Which of the following best explains why water is called the 'universal solvent'?

Accepted Answer

Its polarity allows it to dissolve many different solutes.

Question 18

Which of the following is a real-world consequence of ocean acidification?

Accepted Answer

Reduced growth of coral reefs due to decreased calcium carbonate.

Question 19

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

Accepted Answer

Acids have pH less than 7, bases have pH greater than 7, and neutral solutions have pH equal to 7.

Question 20

Which of the following is an example of a buffer system in the human body?

Accepted Answer

The bicarbonate buffer system, which helps maintain blood pH.

The Chemical Basis of Life: Water’s Life-Supporting Properties

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