Q: If the pH of a solution is 2, what is the concentration of hydrogen ions $$[H^+] in $$the solution?

$$[H^+] = 1 \times 10$$^{-2}$$\ \mathrm{M}$$

Question 1

Which property of water is primarily responsible for the ability of insects, such as water striders, to walk on the surface of ponds?

Accepted Answer

High surface tension due to cohesion

Question 2

A solution is prepared by dissolving 58 g of NaCl (molecular mass = 58 g/mol) in enough water to make 1 liter of solution. What is the molarity of NaCl in this solution?

Accepted Answer

$$1\ \mathrm{M}$$

Question 3

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

Accepted Answer

Hydrogen bonds in ice create a crystalline lattice that spaces molecules farther apart.

Question 4

What is the pH of a solution with a hydrogen ion concentration $$[H^+] = 1.0 	imes 10$$^{-4}$$\ \mathrm{M}$$?

Accepted Answer

$$pH = 4$$

Question 5

Which of the following substances would water NOT dissolve effectively?

Accepted Answer

Vegetable oil

Question 6

A buffer solution contains a weak acid and its corresponding base. What is the main function of this buffer in biological systems?

Accepted Answer

To maintain a constant pH by minimizing changes in $$[H^+]$$ and $$[OH^-]$$

Question 7

Which of the following best describes the difference between hydrophobic and hydrophilic substances?

Accepted Answer

Hydrophobic substances have nonpolar bonds and do not dissolve in water; hydrophilic substances have polar or ionic bonds and dissolve in water.

Question 8

If the pH of a solution is 2, what is the concentration of hydrogen ions $$[H^+] in $$the solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-2}$$\ \mathrm{M}$$

Question 9

Which of the following is a direct consequence of water’s high specific heat for life on Earth?

Accepted Answer

Stable environmental temperatures that support diverse life forms

Question 10

A scientist adds 0.7893 mol of NH$$_4Cl to $$enough water to make 0.5000 L of solution. What is the molarity of the solution?

Accepted Answer

$$1.579\ \mathrm{M}$$

Question 11

Which of the following equations correctly defines pH?

Accepted Answer

$$pH = -\log [H^+]$$

Question 12

Ocean acidification is primarily caused by which process?

Accepted Answer

Absorption of excess CO$$_2$$ from the atmosphere by seawater

Question 13

Which of the following best describes the role of hydrogen bonds in water’s ability to moderate temperature?

Accepted Answer

Hydrogen bonds allow water to absorb or release large amounts of heat with little change in temperature.

Question 14

A solution is made by mixing 3.60 x $$10^{-3}$$ mol of NaOH and 5.95 x $$10^{-4}$$ mol of HCl in enough water to make 1.00 L. What is the pH of the resulting solution? (Assume complete dissociation and that NaOH and HCl neutralize each other.)

Accepted Answer

$$pH \approx 11.8$$

Question 15

Which of the following is NOT one of the four emergent properties of water that contribute to Earth’s suitability for life?

Accepted Answer

Ability to act as a buffer

Question 16

What happens to carbonate ions in seawater as a result of ocean acidification?

Accepted Answer

They combine with protons to form bicarbonate ions, reducing carbonate available for organisms.

Question 17

Which of the following best describes a hydration shell?

Accepted Answer

A layer of water molecules surrounding an ion in solution

Question 18

If a solution has a pH of 8, what is its pOH?

Accepted Answer

$$pOH = 6$$

Question 19

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

Accepted Answer

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

Question 20

Which of the following is a real-world consequence of the expansion of water upon freezing?

Accepted Answer

Ice forms on the surface of lakes, insulating the water below and allowing aquatic life to survive in winter.

Water and Life: Properties, Chemistry, and Biological Importance

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