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Chemistry: The Central Science, 12e (Brown et al.)
Chapter 18 Chemistry of the Environment
18.1 Multiple-Choice Questions
1) In the troposphere, temperature __________ with increasing altitude, while in the stratosphere,
temperature __________ with increasing altitude.
A) increases, increases
B) decreases, decreases
C) increases, decreases
D) decreases, increases
E) decreases, remains constant
2) Which of the following is (are) not a typical source of carbon dioxide?
A) decomposition of organic matter
B) release from oceans
C) combustion of fossil fuels
D) atmospheric electrical discharges
E) all of the above
3) Which of the following is arranged correctly in order of increasing distance from Earth's surface?
A) mesosphere < troposphere < stratosphere < thermosphere
B) troposphere < mesosphere < stratosphere < thermosphere
C) troposphere < mesosphere < thermosphere < stratosphere
D) troposphere < stratosphere < mesosphere < thermosphere
E) mesosphere < troposphere < thermosphere < stratosphere
4) The area of the Earth's atmosphere 10-50 km above the surface is called the __________.
A) thermosphere
B) mesosphere
C) mesopause
D) stratosphere
E) troposphere
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5) Which of the following is not released by the combustion of fossil fuels?
A) CO2
B) SO2
C) CH4
D) NO
E) O3
6) The partial pressure of a gas in air is 1.20 torr and its concentration is 2.80 x 103 ppm. The total air
pressure is __________ torr.
A) 1.2
B) 429
C) 760
D) 2333
E) 2800
7) As one gains altitude in the atmosphere, based on the ionization energies shown below, which
sequence of mole fractions is the correct one?
Process Ionization Energy (kJ/mol)
N2 + hν → N2+ + e- 1495
O2 + hν → O2+ + e- 1205
O + hν → O+ + e- 1313
NO + hν → NO+ + e- 890
A) N2 > N > NO > O2
B) N2 > O > O2 > NO
C) N2 > O2 > O > NO
D) NO > O2 > O > N2
E) All will be equal.
8) Why does the upper atmosphere contain only very little dissociated nitrogen?
A) most of the nitrogen is in the troposphere and not in the upper atmosphere
B) the dissociated nitrogen very rapidly diffuses out of the atmosphere and into space
C) nitrogen atoms are extremely reactive and so react with other substances immediately upon their
formation
D) the bond energy of nitrogen is very high and it does not absorb radiation very efficiently
E) There is no N2 in the upper atmosphere.
9) Of the compounds below, the one that requires the shortest wavelength for photoionization is
__________.
A) O
B) O2
C) NO
D) N2
E) They all require the same wavelength.
10) What is the wavelength of a photon with just enough energy to break a CN bond? (The bond energy
of the CN bond is 891 kJ/mole.)
A) 242 nm
B) 304 nm
C) 134 nm
D) 186 nm
E) 275 nm
11) Photoionization processes (e.g., N2 + hν → N2+ + e-) remove UV of <150 nm. Which
photoreaction is the principal absorber of UV in the 150-200 nm range in the upper atmosphere?
A) N2 + hν → 2N
B) O2 + hν → 2O
C) O3 + hν → O2 + O
D) N2 + O2 + hν → 2NO
E) NO + O2 + hν → NO3
12) The majority of ozone that protects against the high energy radiation of the sun is found in the
__________.
A) thermosphere
B) mesosphere
C) mesopause
D) stratosphere
E) troposphere
13) Why does ozone not form in high concentrations in the atmosphere above 50 km?
A) Insufficient oxygen is available.
B) Insufficient molecules exist for removal of excess energy from ozone upon its formation.
C) Light of the required wavelength is not available at those altitudes.
D) Atomic oxygen concentration is too low at high altitudes.
E) The pressure is too high.
14) Of the reactions involved in the photodecomposition of ozone (shown below), which are
photochemical?
1. O2 (g) + hν → O (g) + O (g)
2. O (g) + O2 (g) + M (g) → O3 (g) + M* (g)
3. O3 (g) + hν → O2 (g) + O (g)
4. O (g) + O (g) + M (g) → O2 (g) + M* (g)
A) 2 and 4
B) 1, 2, and 4
C) 1 and 3
D) 1 only
E) all of them
15) Of the reactions involved in the photodecomposition of ozone (shown below), which are
exothermic?1. O2 (g) + hν → O (g) + O (g)
2. O (g) + O2 (g) + M (g) → O3(g) + M* (g)
3. O3 (g) + hν → O2 (g) + O (g)
4. O (g) + O (g) + M (g) → O2 (g) + M* (g)
A) 2 and 4
B) 1 and 3
C) 1, 2, and 4
D) 2 only
E) all of them
16) In the reactions involved in the photodecomposition of ozone (shown below), what does M
symbolize?
1. O2 (g) + hν → O (g) + O (g)
2. O (g) + O2 (g) + M (g) → O3 (g) + M* (g)
3. O3 (g) + hν → O2 (g) + O (g)
4. O (g) + O (g) + M (g) → O2 (g) + M* (g)
A) mesosphere
B) metal
C) molybdenum
D) methane
E) molecule
17) Why are chlorofluorocarbons so damaging to the ozone layer when they are such stable molecules?
A) They contain a double bond that ozone readily attacks, resulting in the destruction of the ozone.
B) They are very light molecules that rapidly diffuse into the upper atmosphere and block the radiation
that causes formation of ozone.
C) They are greenhouse gases that raise the temperature above the dissociation temperature of ozone.
D) The radiation in the stratosphere dissociates them producing chlorine atoms that catalytically destroy
ozone.
E) CFCs do not damage the ozone.
18) Cl atoms formed via photolysis of C Cl bonds of chlorofluorocarbons in the stratosphere are
particularly effective in destroying ozone at these altitudes because __________.
A) Cl atoms absorb UV, which generate O atoms to react with O2 to produce ozone
B) Cl atoms catalytically convert O3 to O2
C) Cl atoms stoichiometrically convert O3 to O2
D) Cl atoms react with H atoms, which catalyze conversion of O2 to O3
E) Cl atoms react with N atoms, which catalyze conversion of O2 to O3
19) Select the substance that is thought to be partially responsible for depleting the concentration of
ozone in the stratosphere.
A) CFCl3
B) CO2
C) O2
D) N2
E) He
20) In the past, CFCs were not used in __________.
A) spray cans
B) plastic manufacturing
C) air conditioners
D) refrigerators
E) dry cleaning
21) Which one of the following is a source of carbon dioxide in the troposphere?
A) natural gas seepage
B) electrical discharges
C) fossil-fuel combustion
D) volcanic gases
E) forest fires
22) The source(s) of sulfur dioxide in the atmosphere is/are __________.
A) volcanic gases
B) forest fires
C) bacterial action
D) fossil-fuel combustion
E) all of the above
23) Of the following, only __________ does not result in the formation of acid rain.
A) carbon dioxide
B) nitrogen dioxide
C) sulfur dioxide
D) nitrogen monoxide
E) methane
24) Sulfur released into the troposphere arises from both natural and human activity. What is the ratio of
human to natural sources of sulfur compounds?
A) 3:1
B) 2:1
C) 1:1
D) 1:2
E) 1:3
25) How does lime reduce sulfur dioxide emissions from the burning of coal?
A) It reacts with the sulfur dioxide to form calcium sulfite solid that can be precipitated.
B) It reduces the sulfur dioxide to elemental sulfur that is harmless to the environment.
C) It oxidizes the sulfur dioxide to tetrathionate that is highly water soluble so it can be scrubbed from
the emission gases.
D) It catalyzes the conversion of sulfur dioxide to sulfur trioxide which is much less volatile and can be
removed by condensation.
E) It converts SO2 to solid, elemental sulfur.
26) The cumulative result of carbon dioxide, methane, and ozone in the troposphere on atmospheric
temperatures is referred to as __________.
A) acid rain
B) the greenhouse effect
C) photoionization
D) photochemical smog
E) photodissociation
27) Carbon dioxide contributes to atmospheric warming by __________.
A) absorbing incoming radiation from the sun and converting it to heat
B) absorbing radiation emitted from the surface of the earth preventing its loss to space
C) undergoing exothermic reactions extensively in the atmosphere
D) increasing the index of refraction of the atmosphere so that infrared radiation from the sun is
refracted to the surface of the earth where it is converted to heat
E) reducing the concentration of CO in the atmosphere.
28) Which one of the following substances found in the atmosphere will absorb radiation in the infrared
portion of the spectrum?
A) N2
B) O2
C) Kr
D) H2O
E) He
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29) Which gaseous sulfur compound combines with water to form the principal acidic constituent of
acid rain?
A) H2SO4
B) SO2
C) SO
D) SO3
E) H2S
30) The reaction that forms most of the acid in acid rain is __________.
A) SO2 (g) + H2O (l) → H2SO4 (aq)
B) SO2 (g) + H2O (l) → H2SO3 (aq)
C) H2S (g) + 2 O2 (g) → H2SO4 (l)
D) Cl2 (g) + H2O (l) → HCl (aq) + HClO (aq)
E) SO3 (g) + H2O (l) → H2SO4 (aq)
31) Incomplete combustion of carbon-containing materials occurs when __________.
A) there is insufficient oxygen to convert all of the carbon to carbon dioxide
B) there are sulfur impurities in the carbon-containing material
C) the carbon-containing material is a gas
D) the combustion flame is too hot
E) there is an excess of oxygen
32) What is meant by the salinity of seawater?
A) percent by mass of salt in seawater
B) mass in grams of dry salts present in 1 kg of seawater
C) molality of NaCl in seawater
D) osmotic pressure of seawater
E) molarity of NaCl in seawater
33) The concentration of Mg in seawater is 0.054 M. How many grams of Mg can be extracted from
10.0 kg of seawater if the recovery rate is 20.0%?
A) 13.9
B) 6.50
C) 11.3
D) 2.60
E) 5.25
34) A single individual typically uses the greatest quantity of water for __________.
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A) flushing toilets
B) cooking
C) cleaning (bathing, laundering, and house cleaning)
D) watering lawns
E) drinking water
35) The main ionic constituent of sea water is __________.
A) Na+
B) Cl-
C) SO4-2
D) Mg+2
E) Ca+2
36) To produce acceptable quality drinking water from seawater by desalination, the level of salt must
be reduced __________ fold.
A) 10
B) 50
C) 70
D) 100
E) 120
37) The primary detrimental effect of the presence of large amounts of biodegradable organic materials
in water is __________.
A) it causes death of bottom dwelling organisms because it agglutinates and settles to the bottom,
poisoning bottom dwelling organisms
B) it causes oxygen depletion in the water
C) it rises to the surface and absorbs wavelengths needed by aquatic plants
D) it decomposes endothermically causing the temperature of the water to decrease below the limits
within which most aquatic organisms can live
E) it causes the water to become murky
38) What is the final stage in municipal water treatment?
A) filtration through sand and gravel
B) aeration
C) settling
D) treatment with ozone or chlorine
E) removal of added fluoride
39) Which of the following is not a stage in water treatment?
A) coarse filtration
B) aeration
C) chlorination
D) distillation
E) settling
40) In the presence of oxygen, the nitrogen present in biodegradable material ends up mainly as
__________.
A) NH3
B) NH4+
C) NO
D) NO2
E) NO3-
41) Chemical treatment of municipal water supplies commonly entails use of CaO, Al2(SO4)3, and Cl2.
The purpose of adding CaO is to __________.
A) remove all HCO3- as solid CaCO3
B) remove all SO42- as solid CaSO4
C) remove all Cl- as solid CaCl2
D) selectively kill anaerobic (but not aerobic) bacteria
E) make the water slightly basic so that addition of Al2(SO4)3 will afford a gelatinous precipitate of
Al(OH)3
42) Which one of the following could be produced by anaerobic bacteria decomposing biodegradable
waste?
A) nitrate
B) sulfate
C) carbon dioxide
D) hydrogen sulfide
E) water
43) Eutrophication of a lake is the process of __________.
A) rapid increase in the amount of dead and decaying plant matter in the lake as a result of excessive
plant growth
B) rapid decline in the lake's pH due to acid rain
C) dissolved oxygen being depleted by an overpopulation of fish
D) stocking the lake with fish
E) restoration of the lake's dissolved oxygen supply by aerobic bacteria
44) The lime-soda process is used for large-scale water-softening operations. CaO is added to
__________.
A) oxidize Fe2+ to insoluble Fe2O3
B) cause precipitation of magnesium as Mg(OH)2
C) remove most Al3+ as solid Al(OH)3
D) cause precipitation of iron and magnesium as Fe2MgO4
E) reduce the pH to 3-4
45) Water containing high concentrations of __________ cations is called hard water.
A) Ca2+
B) Mg2+
C) Na+
D) K+
E) Ca2+ or Mg2+
46) THMs are __________.
A) non-toxic
B) natural
C) used in green chemistry
D) suspected carcinogens
E) atmospheric pollutants
47) Which of the following is not one of the 12 principles associated with green chemistry?
A) use of renewable feedstocks
B) design of safer chemicals
C) less hazardous chemical synthesis
D) design for degradation
E) reduction in the use of catalytic reagents
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48) Which of the following is classified as a supercritical fluid?
A) water
B) xylene
C) toluene
D) hydrogen peroxide
E) none of the above
18.2 Bimodal Questions
1) The layer of the atmosphere that contains our weather is called the __________.
A) mesosphere
B) heterosphere
C) stratosphere
D) thermosphere
E) troposphere
2) Of the noble gases, __________ is present in highest concentration in dry air at sea level.
A) Ne
B) He
C) Xe
D) Kr
E) Ar
3) The dividing line between the troposphere and stratosphere is known as the __________.
A) mesosphere
B) tropopause
C) thermosphere
D) stratopause
E) mesopause
4) The pressure of the atmosphere __________.
A) increases with altitude
B) follows the same trend as temperature
C) decreases with altitude
D) follows the reverse trend as temperature
E) stays the same
5) What is/are the product(s) of photodissociation of molecular oxygen?
A) molecular nitrogen
