- Chapter 3-Water and Life
1) In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by
.
A) hydrogen bonds
B) nonpolar covalent bonds
C) polar covalent bonds
D) ionic bonds
Answer: C
2) The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. What is this attraction called?
A) a covalent bond
B) a hydrogen bond
C) an ionic bond
D) a van der Waals interaction
Answer: B
3) The partial negative charge in a molecule of water occurs because _.
A) the oxygen atom donates an electron to each of the hydrogen atoms
B) the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus
C) the oxygen atom has two pairs of electrons in its valence shell that are not neutralized by hydrogen atoms
D) one of the hydrogen atoms donates an electron to the oxygen atom
Answer: B
4) Sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. Compared to water molecules, molecules of H2S will .
A) have greater cohesion to other molecules of H2S
B) have a greater tendency to form hydrogen bonds with each other
C) have a higher capacity to absorb heat for the same change in temperature
D) not form hydrogen bonds with each other
Answer: D
5) Water molecules can form hydrogen bonds with .
A) compounds that have polar covalent bonds
B) oils
C) oxygen gas (O2) molecules
D) chloride ions
Answer: A
6) Which of the following is a property of liquid water? Liquid water .
A) is less dense than ice
B) has a specific heat that is lower than that for most other substances
C) has a heat of vaporization that is higher than that for most other substances
D) is nonpolar
Answer: C
7) Which of the following can be attributed to water’s high specific heat?
A) Oil and water do not mix well.
B) A lake heats up more slowly than the air around it.
C) Ice floats on water.
D) Sugar dissolves in hot tea faster than in iced tea.
Answer: B
8) The cities of Portland, Oregon, and Minneapolis, Minnesota, are at about the same latitude, but Minneapolis has much hotter summers and much colder winters than Portland. Why?
A) They are not at the same exact lati
B) The ocean near Portland moderates the temperature.
C) Fresh water is more likely to freeze than salt water.
D) Minneapolis is much windier, due to its location in the middle of North America
Answer: B
9) To act as an effective coolant in a car’s radiator, a substance has to have the capacity to absorb a great deal of heat. You have a reference book with tables listing the physical properties of many liquids. In choosing a coolant for your car, which table would you check first?
A) pH
B) density at room temperature
C) heat of vaporization
D) specific heat
Answer: D
10) Water has many exceptional and useful properties. Which is the rarest property among compounds?
A) Water is a solvent.
B) Solid water is less dense than liquid water
C) Water has a high heat capacity.
D) Water has surface tension
Answer: B
11) Which of the following effects can occur because of the high surface tension of water?
A) Lakes cannot freeze solid in winter, despite low temperatures.
B) A raft spider can walk across the surface of a small pond.
C) Organisms can resist temperature changes, although they give off heat due to chemical reaction
D) Sweat can evaporate from the skin, helping to keep people from overheating.
Answer: B
12) Which of the following takes place as an ice cube cools a drink?
A) Molecular collisions in the drink increase.
B) Kinetic energy in the liquid water decrease
C) A calorie of heat energy is transferred from the ice to the water of the drink
D) The specific heat of the water in the drink decreases.
Answer: B
13) A dietary Calorie equals 1 kilocalorie. Which of the following statements correctly defines 1 kilocalorie? One kilocalorie equals .
A) 1000 calories, or the amount of heat required to raise the temperature of 1 g of water by 1°C
B) 10,000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1°F
C) 1000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1°C
D) 1000 calories, or the amount of heat required to raise the temperature of 100g of water by 100°C
Answer: C
14) Which type of bond must be broken for water to vaporize?
A) ionic bonds
B) polar covalent bonds
C) hydrogen bonds
D) both polar covalent bonds and hydrogen bonds
Answer: C
15) Why does ice float in liquid water?
A) The high surface tension of liquid water keeps the ice on top.
B) The ionic bonds between the molecules in ice prevent the ice from sinking.
C) Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.
D) The crystalline lattice of ice causes it to be denser than liquid water.
Answer: C
16) Hydrophobic substances such as vegetable oil are .
A) nonpolar substances that repel water molecules
B) nonpolar substances that have an attraction for water molecules
C) polar substances that repel water molecules
D) polar substances that have an affinity for water
Answer: A
17) One mole (mol) of glucose (molecular mass = 180 daltons) is .
A) 180 × 1023 molecules of glucose
B) 1 kilogram of glucose dissolved in 1 liter of solution
C) 180 kilograms of glucose
D) 180 grams of glucose
Answer: D
18) When an ionic compound such as sodium chloride (NaCl) is placed in water, the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of solute particles (molecules or ions)?
A) 1 liter of 0.5 M NaCl
B) 1 liter of 0 M NaCl
C) 1 liter of 0 M glucose
D) 1 liter of 1.0 M NaCl and 1 liter of 0 M glucose will contain equal numbers of solute particles.
Answer: B
19) The molar mass of glucose is 180 grams per mole (g/mol). Which of the following procedures should you carry out to make a 1 M solution of glucose? Into 0.8 liter (L) of water, dissolve .
A) 1 g of glucose and then add more water until the total volume of the solution is 1 L
B) 18 g of glucose and then add more water until the total volume of the solution is 1 L
C) 180 g of glucose and then add 0.2 L more of water
D) 180 g of glucose and then add more water until the total volume of the solution is 1 L
Answer: D
20) You have a freshly prepared 0.1 M glucose solution. Each liter of this solution contains how many glucose molecules?
A) 02 × 1023
B) 3.01 × 1023
C) 6.02 × 1024
D) 02 × 1022
Answer: D
21) Based on your knowledge of the polarity of water molecules, the solute molecule depicted here is most likely .
A) positively charged
B) negatively charged
C) without charge
D) nonpolar
Answer: A
22) One mole of the compound above would weigh how many grams? (Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.)
A) 29
B) 30
C) 60
D) 150
Answer: C
23) How many grams of the compound in the figure above are required to make 1 liter of a 0.5 M solution? (Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.)
A) 29
B) 30
C) 60
D) 150
Answer: B
24) Identical heat lamps are arranged to shine on two identical containers, one containing water and one methanol (wood alcohol), so that each liquid absorbs the same amount of energy minute by minute. The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. Which of the following graphs correctly describes what will happen to the temperature of the water and the methanol?
Answer: B
25) You have two beakers. One contains pure water, the other contains pure methanol (wood alcohol). The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. You pour crystals of table salt (NaCl) into each beaker. Predict what will happen.
A) Equal amounts of NaCl crystals will dissolve in both water and methanol
B) NaCl crystals will not dissolve in either water or methanol.
C) NaCl crystals will dissolve readily in water but will not dissolve in metha
D) NaCl crystals will dissolve readily in methanol but will not dissolve in water
Answer: C
26) Rank, from low to high, the pH of blood, stomach acid, and urine.
A) blood, urine, and stomach acid
B) stomach acid, blood, and urine
C) urine, blood, stomach acid
D) stomach acid, urine, blood
Answer: D
27) A solution with a pH of 5 has how many more protons in it than a solution with a pH of 7?
A) 5 times
B) 10 times
C) 100 times
D) 1000 times
Answer: C
28) Consider the following reaction at equilibrium: What would be the effect of adding additional H2CO3?
A) It would drive the equilibrium dynamics to the rig
B) It would drive the equilibrium dynamics to the left.
C) Nothing would happen, because the reactants and products are in equilibrium.
D) The amounts of CO2 and H2O would decrease.
Answer: B
29) A strong acid like HCl .
A) dissociates completely in an aqueous solution
B) increases the pH when added to an aqueous solution
C) reacts with strong bases to create a buffered solution
D) is a strong buffer at low pH
Answer: A
30) Which of the following dissociates completely in solution and is considered to be a strong base (alkali)?
A) HCl
B) NH3
C) H2CO3
D) NaOH
Answer: D
31) A 0.01 M solution of a substance has a pH of 2. What can you conclude about this substance?
A) It is a strong acid that dissociates completely in water.
B) It is a strong base that dissociates completely in water.
C) It is a weak ac
D) It is a weak base.
Answer: A
32) A solution contains 0.0000001 (10-7) moles of hydroxyl ions [OH-] per liter. Which of the following best describes this solution?
A) acidic: H+ acceptor
B) basic: H+ acceptor
C) acidic: H+ donor
D) neutral
Answer: D
33) What is the pH of a solution with a hydroxyl ion (OH-) concentration of 10-12 M?
A) pH 2
B) pH 4
C) pH 10
D) pH 12
Answer: A
34) Which of the following solutions would require the addition of the greatest amount of base to bring the solution to neutral pH?
A) gastric juice at pH 2
B) vinegar at pH 3
C) black coffee at pH 5
D) household bleach at pH 12
Answer: A
35) What is the hydrogen ion (H+) concentration of a solution of pH 8?
A) 8 M
B) 8 x 10-6 M
C) 10-8 M
D) 10-6 M
Answer: C
36) If the pH of a solution is decreased from 9 to 8, it means that the concentration of .
A) H+ has decreased to one-tenth (1/10) what it was at pH 9
B) H+ has doubled compared to what it was at pH 9
C) H+ has increased tenfold (10X) compared to what it was at pH 9
D) OH- has increased tenfold (10X) compared to what it was at pH 9
Answer: C
37) One liter of a solution of pH 2 has how many more hydrogen ions (H+) than 1 liter of a solution of pH 6?
A) 4 times more
B) 40,000 times more
C) 10,000 times more
D) 100,000 times more
Answer: C
38) Which of the following statements is true about buffer solutions?
A) They maintain a constant pH when bases are added to them but not when acids are added to them.
B) They maintain a constant pH when acids are added to them but not when bases are added to them.
C) They fluctuate in pH when either acids or bases are added to the
D) They maintain a relatively constant pH when either acids or bases are added to the Answer: D
39) One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+), as noted below.
If the pH of blood drops, one would expect .
A) a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-
B) the concentration of bicarbonate ions (HCO3-) to increase
C) the HCO3- to act as a base and remove excess H+ by the formation of H2CO3
D) the HCO3- to act as an acid and remove excess H+ by the formation of H2CO3
Answer: C
40) One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+), as noted below.
If the pH of blood increases, one would expect .
A) a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-
B) an increase in the concentration of H2CO3 and a decrease in the concentration of HCO3-
C) a decrease in the concentration of HCO3- and an increase in the concentration of H+
D) an increase in the concentration of HCO3- and a decrease in the concentration of OH-
Answer: A
41) Assume that acid rain has lowered the pH of a particular lake to pH 4.0. What is the hydroxide ion concentration of this lake?
A) 1 × 10-10 mol of hydroxide ions per liter of lake water
B) 1 × 10-4 mol of hydroxide ions per liter of lake water
C) 4.0 M with regard to hydroxide ion concentration
D) 0 × 10-4 mol of hydroxide ions per liter of lake water
Answer: A
42) Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this
information, we can reasonably conclude that .
A) solution Y has no free hydrogen ions (H+)
B) the concentration of hydrogen ions in solution Y is 1000 times as great as the concentration of hydrogen ions in solution X
C) the concentration of hydrogen ions in solution X is 3 times as great as the concentration of hydrogen ions in solution Y
D) the concentration of hydrogen ions in solution X is 1000 times as great as the concentration of hydrogen ions in solution Y
Answer: D
43) A beaker contains 100 milliliters (mL) of NaOH solution at pH = 13. A technician carefully pours into the beaker 10 mL of HCl at pH = 1. Which of the following statements correctly describes the result of this mixing?
A) The concentration of Na+ ions will r
B) The pH of the beaker’s contents will increase.
C) The pH of the beaker’s contents will be neutral.
D) The pH of the beaker’s contents will decrease. Answer: D
44) Increased atmospheric CO2 concentrations might have what effect on seawater?
A) Seawater will become more alkaline, and carbonate concentrations will decrease.
B) There will be no change in the pH of seawater, because carbonate will turn to bicarbonate.
C) Seawater will become more acidic, and carbonate concentrations will decrease.
D) Seawater will become more acidic, and carbonate concentrations will increase.
Answer: C
45) How would acidification of seawater affect marine organisms? Acidification of seawater would .
A) increase dissolved carbonate concentrations and promote faster growth of corals and shell- building animals
B) decrease dissolved carbonate concentrations and promote faster growth of corals and shell- building animals
C) increase dissolved carbonate concentrations and hinder growth of corals and shell-building animals
D) decrease dissolved carbonate concentrations and hinder growth of corals and shell-building animals
Answer: D
46) One idea to mitigate the effects of burning fossil fuels on atmospheric CO2 concentrations is to pipe liquid CO2 into the ocean at depths of 2500 feet or greater. At the high pressures at such depths, CO2 is heavier than water. What potential effects might result from implementing such a scheme?
A) increased carbonate concentrations in the deep waters
B) increased growth of corals from a change in the carbonate–bicarbonate equilibrium
C) no effect because carbon dioxide is not soluble in water
D) increased acidity and decreased carbonate concentrations in the deep waters
Answer: D
47) If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, then the concentration of H+ ions .
A) is 10 times higher in the cytoplasm than in the mitochondrial matrix
B) is 10 times higher in the mitochondrial matrix than in the cytoplasm
C) in the cytoplasm is 7/8 the concentration in the mitochondrial matrix
D) in the cytoplasm is 8/7 the concentration in the mitochondrial matrix
Answer: A
48) Carbon dioxide (CO2) is readily soluble in water, according to the equation CO2 + H2O ↔ H2CO3. Carbonic acid (H2CO3) is a weak acid. If CO2 is bubbled into a beaker containing pure, freshly distilled water, which of the following graphs correctly describes the results?
Answer: B
49) The loss of water from a plant by transpiration cools the leaf. Movement of water in transpiration requires both adhesion to the conducting walls and wood fibers of the plant and cohesion of the molecules to each other. A scientist wanted to increase the rate of transpiration of a crop species to extend its range into warmer climates. The scientist substituted a nonpolar solution with an atomic mass similar to that of water for hydrating the plants. What do you expect the scientist’s data will indicate from this experiment?
A) The rate of transpiration will be the same for both water and the nonpolar substance.
B) The rate of transpiration will be slightly lower with the nonpolar substance as the plant will not have evolved with the nonpolar compound
C) Transpiration rates will fall to zero as nonpolar compounds do not have the properties necessary for adhesion and cohesion.
D) Transpiration rates will increase as nonpolar compounds undergo adhesion and cohesion with wood fibers more readily than water.
Answer: C
50) In living systems molecules involved in hydrogen bonding almost always contain either oxygen or nitrogen or both. How do you explain this phenomenon?
A) Oxygen and nitrogen are elements found in both nucleic acids and protein
B) Oxygen and nitrogen are elements with very high attractions for their elec
C) Oxygen and nitrogen are elements found in fats and carbohydrates.
D) Oxygen and nitrogen were both components of gases that made up the early atmosphere on Earth.
Answer: B