EPA 608 CERTIFICATION CORE PRACTICE TEST 2026/2027 |
100% Correct Answers with Complete Solutions | Section 608
Exam Prep | Pass Guaranteed - A+ Graded
Domain 1: Ozone Depletion & Environmental Science (12 Questions)
Q1: Which type of ultraviolet radiation is primarily absorbed by the stratospheric ozone
layer, and what are the main human health effects if this protection is reduced?
A. UV-A radiation; primarily causes sunburn and temporary skin reddening
B. UV-B radiation; increased skin cancer, cataracts, and immune system suppression
[CORRECT]
C. UV-C radiation; causes immediate skin damage and genetic mutations in all exposed
organisms
D. UV-A and UV-C equally; primarily affects marine ecosystems and fish populations
Correct Answer: B
Rationale: The stratospheric ozone layer (located 10-30 miles above Earth) absorbs
approximately 95-99% of the sun's UV-B radiation (280-315 nm wavelength). UV-B is the
most biologically damaging form of ultraviolet radiation that reaches the Earth's
surface. When ozone is depleted, increased UV-B penetration causes: (1) increased
incidence of non-melanoma and melanoma skin cancers in humans, (2) cataracts and
other eye damage, (3) suppression of immune system responses, and (4) damage to
crops and marine phytoplankton.
,Option A is incorrect because UV-A (315-400 nm) passes through the ozone layer
relatively unaffected and causes tanning and aging but is less directly responsible for
the cancers and cataracts associated with ozone depletion. Option C is incorrect
because UV-C (100-280 nm) is almost entirely absorbed by the atmosphere and does
not reach the surface in significant amounts. Option D is incorrect because UV-C does
not significantly reach the surface, and UV-A passes through largely unfiltered by ozone.
Q2: In the catalytic destruction of ozone by chlorine atoms from CFCs, how many ozone
molecules can one chlorine atom destroy before it is removed from the stratosphere?
A. 1-5 ozone molecules through direct chemical reaction
B. 10-50 ozone molecules through temporary binding
C. 100-1,000 ozone molecules through the chlorine cycle [CORRECT]
D. 10,000-100,000 ozone molecules through permanent free radical status
Correct Answer: C
Rationale: The catalytic ozone destruction cycle involves chlorine atoms (Cl) released
from CFCs and HCFCs through photodissociation in the stratosphere. The chlorine cycle
proceeds as follows: (1) Cl + O₃ → ClO + O₂, (2) ClO + O → Cl + O₂. The chlorine atom is
regenerated and can repeat this cycle approximately 100,000 times before it is
eventually sequestered in reservoir species (HCl, ClONO₂) or transported out of the
stratosphere. However, the net destruction is typically cited as 100-1,000 ozone
molecules per chlorine atom before removal, as not all chlorine participates in the
catalytic cycle continuously due to reservoir formation. This catalytic nature makes
,CFCs and HCFCs extremely potent ozone depleters despite being present in trace
amounts.
Option A and B vastly underestimate the catalytic efficiency. Option D overstates the
typical destruction rate before chlorine is converted to reservoir species that temporarily
remove it from the catalytic cycle.
Q3: Which refrigerant has an Ozone Depletion Potential (ODP) of 1.0, serving as the
reference standard for all other ODP comparisons?
A. R-22 (HCFC-22)
B. R-134a (HFC-134a)
C. R-11 (CFC-11) [CORRECT]
D. R-1234yf (HFO-1234yf)
Correct Answer: C
Rationale: R-11 (trichlorofluoromethane, CFC-11) is assigned an ODP of 1.0 by the
Montreal Protocol and serves as the reference compound for all other ozone-depleting
substances. CFC-11 was widely used as a refrigerant, foam blowing agent, and solvent.
Its molecular structure contains three chlorine atoms and one fluorine atom attached to
a single carbon, making it highly effective at transporting chlorine to the stratosphere
where it photodissociates to release chlorine atoms.
, Option A (R-22) is an HCFC with ODP of 0.055. Option B (R-134a) is an HFC with ODP of
0. Option D (R-1234yf) is an HFO with ODP near 0. The ODP scale is relative to CFC-11's
destructive potential.
Q4: What is the Global Warming Potential (GWP) of R-134a over a 100-year time horizon,
and how does this compare to the GWP of common HFO alternatives?
A. GWP of 1; HFOs have GWP of 0.1-0.5
B. GWP of 1,430; HFOs like R-1234yf have GWP <1 [CORRECT]
C. GWP of 3,920; similar to R-404A and other high-GWP blends
D. GWP of 0; similar to ammonia and carbon dioxide
Correct Answer: B
Rationale: R-134a (1,1,1,2-tetrafluoroethane, HFC-134a) has a 100-year GWP of 1,430,
meaning it traps 1,430 times more heat per unit mass than carbon dioxide over 100
years. This is considered a moderate-to-high GWP. HFO alternatives like R-1234yf
(2,3,3,3-tetrafluoropropene) have GWP <1 (approximately 0.3-0.4), representing a 99.9%
reduction in climate impact compared to R-134a. This dramatic difference drove the
automotive industry's transition to R-1234yf for mobile air conditioning under EPA's
SNAP program.
Option A incorrectly states R-134a's GWP as 1 (that's CO₂'s reference value). Option C
confuses R-134a with R-404A (GWP ~3,920). Option D is incorrect as R-134a has
significant GWP, unlike natural refrigerants (ammonia GWP ~0, CO₂ GWP = 1).
100% Correct Answers with Complete Solutions | Section 608
Exam Prep | Pass Guaranteed - A+ Graded
Domain 1: Ozone Depletion & Environmental Science (12 Questions)
Q1: Which type of ultraviolet radiation is primarily absorbed by the stratospheric ozone
layer, and what are the main human health effects if this protection is reduced?
A. UV-A radiation; primarily causes sunburn and temporary skin reddening
B. UV-B radiation; increased skin cancer, cataracts, and immune system suppression
[CORRECT]
C. UV-C radiation; causes immediate skin damage and genetic mutations in all exposed
organisms
D. UV-A and UV-C equally; primarily affects marine ecosystems and fish populations
Correct Answer: B
Rationale: The stratospheric ozone layer (located 10-30 miles above Earth) absorbs
approximately 95-99% of the sun's UV-B radiation (280-315 nm wavelength). UV-B is the
most biologically damaging form of ultraviolet radiation that reaches the Earth's
surface. When ozone is depleted, increased UV-B penetration causes: (1) increased
incidence of non-melanoma and melanoma skin cancers in humans, (2) cataracts and
other eye damage, (3) suppression of immune system responses, and (4) damage to
crops and marine phytoplankton.
,Option A is incorrect because UV-A (315-400 nm) passes through the ozone layer
relatively unaffected and causes tanning and aging but is less directly responsible for
the cancers and cataracts associated with ozone depletion. Option C is incorrect
because UV-C (100-280 nm) is almost entirely absorbed by the atmosphere and does
not reach the surface in significant amounts. Option D is incorrect because UV-C does
not significantly reach the surface, and UV-A passes through largely unfiltered by ozone.
Q2: In the catalytic destruction of ozone by chlorine atoms from CFCs, how many ozone
molecules can one chlorine atom destroy before it is removed from the stratosphere?
A. 1-5 ozone molecules through direct chemical reaction
B. 10-50 ozone molecules through temporary binding
C. 100-1,000 ozone molecules through the chlorine cycle [CORRECT]
D. 10,000-100,000 ozone molecules through permanent free radical status
Correct Answer: C
Rationale: The catalytic ozone destruction cycle involves chlorine atoms (Cl) released
from CFCs and HCFCs through photodissociation in the stratosphere. The chlorine cycle
proceeds as follows: (1) Cl + O₃ → ClO + O₂, (2) ClO + O → Cl + O₂. The chlorine atom is
regenerated and can repeat this cycle approximately 100,000 times before it is
eventually sequestered in reservoir species (HCl, ClONO₂) or transported out of the
stratosphere. However, the net destruction is typically cited as 100-1,000 ozone
molecules per chlorine atom before removal, as not all chlorine participates in the
catalytic cycle continuously due to reservoir formation. This catalytic nature makes
,CFCs and HCFCs extremely potent ozone depleters despite being present in trace
amounts.
Option A and B vastly underestimate the catalytic efficiency. Option D overstates the
typical destruction rate before chlorine is converted to reservoir species that temporarily
remove it from the catalytic cycle.
Q3: Which refrigerant has an Ozone Depletion Potential (ODP) of 1.0, serving as the
reference standard for all other ODP comparisons?
A. R-22 (HCFC-22)
B. R-134a (HFC-134a)
C. R-11 (CFC-11) [CORRECT]
D. R-1234yf (HFO-1234yf)
Correct Answer: C
Rationale: R-11 (trichlorofluoromethane, CFC-11) is assigned an ODP of 1.0 by the
Montreal Protocol and serves as the reference compound for all other ozone-depleting
substances. CFC-11 was widely used as a refrigerant, foam blowing agent, and solvent.
Its molecular structure contains three chlorine atoms and one fluorine atom attached to
a single carbon, making it highly effective at transporting chlorine to the stratosphere
where it photodissociates to release chlorine atoms.
, Option A (R-22) is an HCFC with ODP of 0.055. Option B (R-134a) is an HFC with ODP of
0. Option D (R-1234yf) is an HFO with ODP near 0. The ODP scale is relative to CFC-11's
destructive potential.
Q4: What is the Global Warming Potential (GWP) of R-134a over a 100-year time horizon,
and how does this compare to the GWP of common HFO alternatives?
A. GWP of 1; HFOs have GWP of 0.1-0.5
B. GWP of 1,430; HFOs like R-1234yf have GWP <1 [CORRECT]
C. GWP of 3,920; similar to R-404A and other high-GWP blends
D. GWP of 0; similar to ammonia and carbon dioxide
Correct Answer: B
Rationale: R-134a (1,1,1,2-tetrafluoroethane, HFC-134a) has a 100-year GWP of 1,430,
meaning it traps 1,430 times more heat per unit mass than carbon dioxide over 100
years. This is considered a moderate-to-high GWP. HFO alternatives like R-1234yf
(2,3,3,3-tetrafluoropropene) have GWP <1 (approximately 0.3-0.4), representing a 99.9%
reduction in climate impact compared to R-134a. This dramatic difference drove the
automotive industry's transition to R-1234yf for mobile air conditioning under EPA's
SNAP program.
Option A incorrectly states R-134a's GWP as 1 (that's CO₂'s reference value). Option C
confuses R-134a with R-404A (GWP ~3,920). Option D is incorrect as R-134a has
significant GWP, unlike natural refrigerants (ammonia GWP ~0, CO₂ GWP = 1).
