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

Q: A student mixes 29.22 g of NaCl in enough water to make 500 mL of solution. What is the molarity $$M of $$the solution? (Molar mass of NaCl = 58.44 g/mol)

$$M = \frac{29.22}{58.44 \times 0.5} = 1.0 M$$

Question 1

Which property of water allows it to moderate Earth's climate by absorbing and releasing heat with minimal temperature change?

Accepted Answer

Its high specific heat capacity, given by $$C = \frac{q}{m \Delta T}$$

Question 2

A scientist observes that water beads up on a waxy leaf surface. Which property of water is primarily responsible for this phenomenon?

Accepted Answer

Cohesion due to hydrogen bonding

Question 3

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Ice has a lower density than liquid water because hydrogen bonds keep water molecules further apart in the solid state

Question 4

Which equation correctly represents the dissociation of water molecules?

Accepted Answer

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

Question 5

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 6

Which of the following best describes a buffer system in biological fluids?

Accepted Answer

A buffer system maintains pH by donating or accepting $$H^+$$ ions as needed

Question 7

Why is water considered a versatile solvent in biological systems?

Accepted Answer

Water's polarity allows it to dissolve both ionic and polar molecules by forming hydration shells

Question 8

A student mixes 29.22 g of NaCl in enough water to make 500 mL of solution. What is the molarity $$M of $$the solution? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$M = \frac{29.22}{58.44 	imes 0.5} = 1.0 M$$

Question 9

Which of the following is NOT a consequence of water's high heat of vaporization?

Accepted Answer

Water boils at a very low temperature

Question 10

Which property of water is most important for the transport of nutrients and waste in plants?

Accepted Answer

Cohesion and adhesion, allowing capillary action

Question 11

A lake resists temperature change throughout the year. Which property of water is responsible for this phenomenon?

Accepted Answer

Water's high specific heat, $$C = \frac{q}{m \Delta T}$$

Question 12

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

Accepted Answer

Water's polar molecules surround Na$$^+$$ and Cl$$^-$$ ions, stabilizing them in solution

Question 13

Which of the following is a direct result of water's ability to form hydrogen bonds?

Accepted Answer

Water molecules stick together, resulting in high cohesion

Question 14

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

Accepted Answer

The solution is basic and has a low $$[H^+]$$

Question 15

Which of the following best describes the effect of acid rain on aquatic ecosystems?

Accepted Answer

Acid rain lowers the pH of water, harming aquatic life by disrupting enzyme function

Question 16

Which of the following is a correct statement about the relationship between acids, bases, and $$H^+$$ concentration?

Accepted Answer

Acids increase $$H^+$$ concentration, while bases decrease it

Question 17

Which of the following is a real-world example of water's role as a solvent?

Accepted Answer

Water dissolves nutrients and minerals in blood plasma for transport in the human body

Question 18

A buffer solution contains a weak acid and its conjugate base. What happens when a small amount of strong acid is added?

Accepted Answer

The weak base neutralizes added $$H^+$$, minimizing pH change

Question 19

Which of the following best explains why water is essential for life on Earth?

Accepted Answer

Water's unique properties, such as cohesion, adhesion, high specific heat, and solvent abilities, support biological processes

Water: Properties, Structure, and Biological Significance – General Biology Study Notes

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