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

$$[H^+] = 1 \times 10$$^{-4}$$ M

Question 1

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

Accepted Answer

Cohesion due to hydrogen bonding

Question 2

A scientist adds salt to water and observes that the temperature at which the water boils increases. Which property of water is most directly affected by this change?

Accepted Answer

Water's high heat of vaporization

Question 3

Which equation correctly represents the dissociation of water into hydronium and hydroxide ions?

Accepted Answer

$$2H_2O \rightarrow H_3O^+ + OH^-$$

Question 4

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice create a lattice structure that is less dense than liquid water

Question 5

Which property of water is most important for the transport of water from roots to leaves in plants?

Accepted Answer

Cohesion and adhesion

Question 6

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

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ M

Question 7

Which of the following best explains why water is considered a universal solvent?

Accepted Answer

Water's polarity allows it to dissolve many ionic and polar substances

Question 8

A buffer solution is added to a strong acid. What is the expected effect on the pH of the solution?

Accepted Answer

The pH will remain relatively stable

Question 9

Which of the following is a direct consequence of water's high specific heat for living organisms?

Accepted Answer

Water helps stabilize internal and external temperatures

Question 10

Which of the following best describes the role of hydrogen bonds in the structure of liquid water?

Accepted Answer

Hydrogen bonds allow water molecules to form transient networks, giving water its unique properties

Question 11

Which of the following equations represents the relationship between pH and hydrogen ion concentration?

Accepted Answer

$$pH = -\log_{10}[H^+]$$

Question 12

A lake is experiencing ocean acidification due to increased atmospheric CO$$_2. $$What is the most likely effect on aquatic life?

Accepted Answer

Decreased pH will make the water more acidic, affecting shell formation in aquatic organisms

Question 13

Which property of water is most responsible for the formation of droplets on a waxed car hood?

Accepted Answer

Cohesion

Question 14

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

Accepted Answer

Evaporation of sweat absorbs heat due to water's high heat of vaporization

Question 15

Which of the following is NOT a property of water that makes life possible?

Accepted Answer

Water's ability to dissolve nonpolar substances

Question 16

A student mixes oil and water in a beaker and observes that they do not mix. Which property of water explains this observation?

Accepted Answer

Water is polar and oil is nonpolar, so they do not interact

Question 17

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

Accepted Answer

Buffers minimize changes in pH when acids or bases are added

Question 18

Which of the following is a consequence of water's high heat of vaporization for Earth's climate?

Accepted Answer

Moderation of temperature in coastal regions due to energy absorption during evaporation

Question 19

Which of the following best explains why water is able to dissolve salts such as NaCl?

Accepted Answer

Water's polar molecules surround and separate the positive and negative ions

Question 20

Which of the following is the correct definition of adhesion in the context of water's properties?

Accepted Answer

The attraction between water molecules and other substances

Key Concepts: Water Chemistry and Its Biological Importance

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