AP Environmental Science Unit 7: Atmospheric Pollution Practice Exam

Assessment for Unit 7: Atmospheric Pollution

Estimated Time: 60 minutes

Exam Details

Questions: 20 total (20 multiple choice)
Time: 60 minutes (recommended)
Topics Covered: Unit 7: Atmospheric Pollution
Format: Multiple Choice questions matching real exam difficulty
Scoring: Instant results with detailed explanations

A. Multiple-Choice Questions (20 Questions)

Select the one best answer for each question.

1. [Skill: 4.A | Topic: 7.1] An air-quality monitoring station downwind of a power plant reports the following average emissions pattern during normal operation: - High sulfur dioxide ($SO_2$) - High carbon dioxide ($CO_2$) - Detectable mercury and other toxic metals in airborne particulates - Elevated particulate matter (PM) Which fuel source is most consistent with these measured emissions?

(A)Coal burned for electricity generation(B)Natural gas burned for electricity generation(C)Uranium used in a nuclear power plant(D)Wind turbines generating electricity

2. [Skill: 1.B | Topic: 7.1] A city experiences heavy morning traffic that emits nitrogen oxides ($NO_x$). On hot, sunny afternoons, the city frequently issues air-quality alerts because ground-level ozone concentrations increase. After several days of similar conditions, the region also reports rainfall with a lower-than-normal pH. Which statement best explains the relationship among these observations?

(A)Ground-level ozone is a primary pollutant emitted directly from vehicle exhaust, and it causes rainfall to become acidic.(B)Nitrogen oxides are secondary pollutants formed in the atmosphere from ozone, and they lower rainwater pH.(C)Nitrogen oxides from combustion can lead to formation of secondary pollutants such as ozone and acids that contribute to acid rain.(D)The increase in ozone is caused primarily by the release of leaded gasoline additives, which also lower the pH of rain.

3. [Skill: 4.A | Topic: 7.1] An environmental science class examines a dataset of average atmospheric lead concentrations measured near a major U.S. highway. Average atmospheric lead concentration (micrograms per cubic meter, $\mu g/m^3$): - 1975: 1.8 - 1980: 1.0 - 1985: 0.35 - 1990: 0.12 - 1995: 0.05 Which conclusion is best supported by the data and is most consistent with U.S. environmental regulation?

(A)EPA regulation under the Clean Air Act reduced lead in the atmosphere by limiting lead use in gasoline, contributing to a long-term decline in airborne lead.(B)Lead levels declined because lead is a secondary pollutant formed when $NO_x$ reacts with sunlight to produce photochemical smog.(C)Lead levels declined primarily because coal-fired power plants stopped emitting $SO_2$, which otherwise converts to lead aerosols.(D)Lead levels declined because nuclear power generation replaced wind energy, reducing particulate emissions from turbines.

Refer to the figure below.

4. [Skill: 4A | Topic: 7.2] [Image Cue]: Line graph, "Hourly Concentrations of NOx and Ozone (O3) in an Urban Area". X-axis: Time of day (6 A.M., 9 A.M., 12 P.M., 3 P.M., 6 P.M., 9 P.M.). Left Y-axis: NOx concentration (ppb). Right Y-axis: O3 concentration (ppb). Key trends: NOx is highest in the early morning (around 9 A.M.) and declines through the afternoon; O3 is low in the morning, increases late morning, peaks mid-to-late afternoon (around 3 P.M.), then declines in the evening. The graph shows hourly concentrations of nitrogen oxides (NOx) and ozone (O3) measured on a sunny summer day in a large city. Which of the following best explains the observed pattern of ozone (O3) concentrations peaking in the afternoon?

(A)O3 is emitted directly from motor vehicles and accumulates during the afternoon rush hour.(B)NOx and VOCs react in the presence of heat and sunlight, producing secondary pollutants such as O3 that build through the afternoon.(C)Trees release O3 directly during photosynthesis, and photosynthesis peaks in the afternoon.(D)O3 forms most rapidly at night because cooler temperatures slow its breakdown.

5. [Skill: 1A | Topic: 7.2] A city experiences frequent summer photochemical smog advisories. Air-quality officials report high concentrations of ground-level ozone on hot, sunny days. The city is surrounded by forested areas. Which statement best explains how VOCs can contribute to photochemical smog in this scenario?

(A)VOCs are primarily produced by the breakdown of ozone in the stratosphere and then transported downward into the city.(B)VOCs such as gasoline vapors can evaporate at room temperature, and trees can also release VOCs that participate in sunlight-driven reactions forming smog.(C)VOCs react with carbon dioxide at night to directly produce ozone, leading to morning ozone peaks.(D)VOCs are formed only when NOx reacts with sunlight, so reducing VOC emissions is unnecessary if NOx is controlled.

6. [Skill: 6A | Topic: 7.2] A metropolitan area proposes two policy packages to reduce photochemical smog: Policy 1: Require catalytic converters and stricter vehicle emissions testing to reduce NOx emissions from cars and trucks. Policy 2: Install vapor-recovery systems at gasoline stations and tighten controls on industrial solvent use to reduce VOC emissions. Based on how photochemical smog forms, which statement best justifies why implementing BOTH policies would likely reduce the frequency and severity of smog events more than implementing only one policy?

(A)Because photochemical smog is emitted directly as ozone, controlling either NOx or VOCs alone has no effect on ozone levels.(B)Because photochemical smog is formed through reactions involving both NOx and VOCs in sunlight, reducing both precursors limits secondary pollutant formation more effectively.(C)Because NOx and VOCs are only harmful indoors, outdoor smog levels will not change unless air-conditioning use is reduced.(D)Because ozone formation is controlled only by temperature, precursor reductions are ineffective without decreasing summer temperatures.

Refer to the figure below.

7. [Skill: 4.A | Topic: 7.3] A meteorologist graphs air temperature versus altitude for two different mornings in the same city. Which of the following temperature profiles best represents a thermal inversion? [Image Cue]: Graph, "Air Temperature vs. Altitude on Two Mornings", x-axis = Temperature (°C), y-axis = Altitude (m). Include two curves: (1) Normal condition where temperature decreases with altitude near the surface; (2) Inversion condition where temperature increases with altitude for the lowest ~500 m, then decreases above that.

(A)Temperature decreases steadily with increasing altitude from the ground up.(B)Temperature increases with altitude near the ground, then decreases with altitude higher up.(C)Temperature is constant with altitude near the ground, then increases with altitude higher up.(D)Temperature is highest at the ground and remains higher than the air aloft at all altitudes.

8. [Skill: 1.A | Topic: 7.3] A city located in a valley reports the following observations on a clear, calm winter morning: - Overnight, the ground cooled rapidly. - Winds are very light. - Drivers report reduced visibility and irritation in the eyes and throat. - Air-quality monitors show elevated particulate matter concentrations near street level. Which explanation best accounts for the observed increase in near-surface air pollution?

(A)A thermal inversion formed, creating a stable layer of warmer air above cooler surface air that prevented vertical mixing and trapped pollutants near the ground.(B)Stratospheric ozone increased overnight, allowing more ultraviolet radiation to reach the surface and directly produce particulate matter.(C)Surface air warmed faster than the air above it, increasing convection and concentrating pollutants near the ground.(D)Increased humidity caused pollutants to chemically react into harmless products, leading to higher measured particulate concentrations.

9. [Skill: 4.B | Topic: 7.3] An environmental science class compares hourly $PM_{2.5}$ concentrations (fine particulate matter) on two days in the same urban area. Data (average $PM_{2.5}$ near the surface): - Day 1 (no inversion): 12 µg/m³ at 7:00, 10 µg/m³ at 12:00, 9 µg/m³ at 17:00 - Day 2 (thermal inversion reported): 28 µg/m³ at 7:00, 26 µg/m³ at 12:00, 20 µg/m³ at 17:00 Which statement best interprets the data using the concept of thermal inversion?

(A)The inversion increased vertical mixing, which kept particulate concentrations higher at the surface throughout the day.(B)The inversion reduced vertical mixing, trapping particulates close to the ground and resulting in higher near-surface concentrations than on Day 1.(C)The inversion converted particulates into gases, causing higher $PM_{2.5}$ readings due to instrument error.(D)The inversion only affects ozone formation and therefore cannot explain differences in $PM_{2.5}$ concentrations.

10. **1. [Skill: 4A | Topic: 7.4]** A monitoring station 15 km downwind of an active volcano recorded atmospheric measurements over 10 days. **Data (daily averages):** - Day 1–3: $CO_2$ = 418–420 ppm; $SO_2$ = 1–2 ppb - Day 4: $CO_2$ = 432 ppm; $SO_2$ = 28 ppb - Day 5: $CO_2$ = 439 ppm; $SO_2$ = 35 ppb - Day 6–10: $CO_2$ returns to 420–422 ppm; $SO_2$ returns to 1–3 ppb Which of the following natural processes most likely explains the short-term increase in atmospheric $CO_2$ shown in the data?

(A)A volcanic eruption released gases, including $CO_2$, into the atmosphere.(B)Increased photosynthesis in nearby vegetation released additional $CO_2$ into the atmosphere.(C)Increased ocean uptake of $CO_2$ caused atmospheric concentrations to rise temporarily.(D)Increased nitrogen fixation by soil bacteria directly released additional $CO_2$ into the atmosphere.

11. **2. [Skill: 4A | Topic: 7.4]** Two air-quality sensors recorded particulate matter during a 24-hour period of strong onshore winds. **Data (24-hour average concentrations):** - Coastal site (1 km from shoreline): $PM_{10}$ = 92 $\mu g/m^3$; $PM_{2.5}$ = 12 $\mu g/m^3$ - Inland site (50 km from shoreline): $PM_{10}$ = 28 $\mu g/m^3$; $PM_{2.5}$ = 11 $\mu g/m^3$ Which natural source most likely explains the much higher $PM_{10}$ at the coastal site while $PM_{2.5}$ remains similar at both sites?

(A)Sea spray producing salt aerosols and coarse particulates near the shoreline(B)Respiration by coastal plants releasing additional $PM_{10}$(C)Stratospheric ozone formation creating additional coarse particles near the coast(D)Deposition of marine sediments into the ocean reducing airborne particles near the shoreline

12. **3. [Skill: 1A | Topic: 7.4]** A student investigates how temperature affects natural atmospheric $CO_2$ sources from soils. The student places equal masses of moist forest soil containing leaf litter into two sealed chambers that initially contain the same $CO_2$ concentration. One chamber is maintained at 5°C and the other at 25°C. No light is provided. After 24 hours, the chamber at 25°C has a substantially higher $CO_2$ concentration than the chamber at 5°C. Which of the following best explains the result?

(A)Higher temperature increased rates of decomposition and cellular respiration, releasing more $CO_2$.(B)Higher temperature increased photosynthesis, releasing more $CO_2$ into the chamber.(C)Higher temperature increased the rate of nitrogen fixation, which directly produces $CO_2$ gas.(D)Higher temperature caused $CO_2$ to be removed from the chamber through condensation onto soil particles.

13. **1. [Skill: 4.A | Topic: 7.5]** A homeowner reports headaches and dizziness that occur mainly in the winter shortly after turning on an older, unvented gas space heater. An indoor air quality technician collects the following measurements in the living room. | Condition | Carbon monoxide (ppm) | Radon (pCi/L) | Total VOCs (relative units) | |---|---:|---:|---:| | Heater OFF (30 min) | 1 | 2.1 | 12 | | Heater ON (30 min) | 28 | 2.0 | 13 | | Windows opened (heater ON, 10 min) | 9 | 2.0 | 13 | Which indoor air pollutant best explains the short-term symptoms and the observed pattern in the data?

(A)Carbon monoxide from incomplete combustion, an asphyxiant that can cause headaches and dizziness(B)Radon-222 produced by decay of uranium in rocks, which causes immediate irritation of the eyes and throat(C)Volatile organic compounds (VOCs) emitted from furniture and carpets, which rapidly increase only when a heater is turned on(D)Lead from older paint, which commonly spikes in air when windows are opened and causes acute dizziness within minutes

14. **2. [Skill: 1.A | Topic: 7.5]** A family moves into a house with a finished basement in a region underlain by uranium-rich granite. A radon test kit left in the basement for several days reports elevated levels of radon. Which statement best identifies the pollutant and describes a major health effect associated with exposure?

(A)Radon-222 is a naturally occurring radioactive gas produced by the decay of uranium in rocks and soils; long-term exposure can cause lung cancer(B)Radon-222 forms primarily from incomplete combustion in gas appliances; short-term exposure causes carbon monoxide–like oxygen deprivation(C)Formaldehyde emitted from new carpeting accumulates in basements; long-term exposure is the second leading cause of lung cancer in America(D)Lead is a naturally occurring radioactive gas that seeps into basements; exposure primarily causes lung cancer through inhalation of the gas

15. 1. [Skill: 4A | Topic: 7.6] A student analyzes vehicle exhaust before and after it passes through an emissions-control device installed in the exhaust system. Exhaust composition (percent by volume) - Before device: CO = 2.0%, NO_x = 0.30%, unburned hydrocarbons = 0.20%, CO_2 = 12.0%, N_2 = 70.0% - After device: CO = 0.2%, NO_x = 0.05%, unburned hydrocarbons = 0.02%, CO_2 = 13.6%, N_2 = 71.2% Which statement best explains how the device reduces air pollutants at the source?

(A)It filters particulate matter out of the exhaust stream, lowering CO and NO_x concentrations without changing the amounts of CO_2 or N_2.(B)It uses catalysts to convert CO and hydrocarbons to CO_2 and H_2O and to convert NO_x to N_2 and O_2, resulting in lower pollutant levels.(C)It cools the exhaust so that CO and hydrocarbons condense and drip out of the tailpipe, reducing emissions of these pollutants.(D)It adds oxygen to the exhaust stream to dilute pollutants, which decreases CO and NO_x concentrations by increasing the total volume of exhaust.

16. 2. [Skill: 1A | Topic: 7.6] A city is trying to reduce air pollution from two sources: Source 1: A gasoline station receives complaints about strong gasoline odors near the pumps, especially on hot days. Source 2: A nearby industrial facility emits an exhaust stream containing both particulate matter and acidic gases. Which combination of pollution-control strategies would best reduce pollutants at the source for BOTH sources?

(A)Install vapor recovery nozzles at the gasoline pumps and install wet or dry scrubbers on the facility’s exhaust stack.(B)Install catalytic converters on the facility’s exhaust stack and plant trees around the gasoline station to absorb gasoline vapors.(C)Switch the gasoline station to a higher-octane fuel and install a baghouse filter on the facility’s exhaust stack to remove both particles and acidic gases.(D)Use conservation practices to reduce gasoline sales and install a catalytic converter on the facility’s exhaust stack to remove particulate matter.

Refer to the figure below.

17. **1. [Skill: 4.A | Topic: 7.7]** A coal-burning power plant is located just west of a mountain range. The prevailing winds are from west to east. Scientists measured the average pH of precipitation at four monitoring stations (A–D) located progressively farther east (downwind) of the plant over the same month. Which of the following best explains the observed downwind decrease in precipitation pH shown in the graph?

(A)Primary particulate matter from the power plant directly lowers precipitation pH as it settles out of the air.(B)Sulfur dioxide released by coal combustion is converted in the atmosphere into sulfuric acid, increasing acid deposition downwind.(C)Carbon dioxide released by the power plant forms carbonic acid, causing severe acid deposition downwind.(D)Chlorofluorocarbons (CFCs) released by the power plant react to form nitric acid, lowering precipitation pH downwind.

18. **2. [Skill: 1.A | Topic: 7.7]** Two regions receive similar amounts of acid deposition over several years. Region L has limestone-rich soil and bedrock, and Region G has granite-rich soil and bedrock. A field study reports the following changes in lake water chemistry. Which of the following best explains why lake pH changes differ between the two regions?

(A)Limestone increases the production of $SO_2$ and $NO_x$ in the atmosphere, causing greater acid deposition in Region L.(B)Limestone-rich soils and bedrock can neutralize added acids, buffering lake water against large pH decreases compared with granite-rich geology.(C)Granite dissolves readily in water, releasing bases that neutralize acid deposition and prevent decreases in lake pH.(D)Acid deposition only affects lakes located near motor vehicles, so geology is not an important factor in lake acidification.

Refer to the figure below.

19. [Skill: 4A | Topic: 7.8] A city public health office measured sound levels near several common urban activities and surveyed residents about health outcomes. [Image Cue]: Table, "Measured Sound Levels and Reported Outcomes", columns: (1) Activity/location, (2) Average sound level (dB), (3) Commonly reported outcome. Rows: (a) Residential street at night: 45 dB, "normal sleep"; (b) Busy arterial road sidewalk: 80 dB, "elevated stress/irritability"; (c) Construction site perimeter: 95 dB, "headaches and difficulty concentrating"; (d) Nightclub interior: 105 dB, "temporary ringing in ears after exposure". Based on the data, which activity/location is most clearly an example of noise pollution as defined in AP Environmental Science because it is at a level high enough to cause hearing loss?

(A)Residential street at night (45 dB), because it can disrupt sleep cycles(B)Busy arterial road sidewalk (80 dB), because it is associated with stress(C)Construction site perimeter (95 dB), because it is louder than normal conversation(D)Nightclub interior (105 dB), because it is associated with temporary ringing in the ears after exposure

Refer to the figure below.

20. [Skill: 2B | Topic: 7.8] Marine biologists studied a coastal whale population before and after a shipping lane was re-routed closer to shore. They recorded average low-frequency background sound levels and the estimated maximum distance over which whale calls could be detected by other whales of the same species. [Image Cue]: Scatter plot, "Background Ocean Noise vs. Whale Call Detection Distance"; x-axis: Background low-frequency sound level (dB), ranging 90 to 120; y-axis: Call detection distance (km), ranging 0 to 10. Trend: strong negative relationship; around 90 dB → ~9–10 km, 100 dB → ~6 km, 110 dB → ~3 km, 120 dB → ~1 km. Which of the following best explains the most likely ecological effect on whales as shipping noise increases, based on the trend shown?

(A)Reduced call detection indicates masking of communication sounds, which can increase stress and interfere with mating, group coordination, or navigation(B)Reduced call detection indicates increased primary productivity, which can shift whales to a lower trophic level(C)Reduced call detection indicates bioaccumulation of heavy metals, which damages whale hearing over multiple generations(D)Reduced call detection indicates ocean acidification, which decreases the amount of dissolved oxygen available for whales

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