EPA 609 PRACTICE EXAM CERTIFICATION STUDY GUIDE AND
PRACTICE QUESTION AND CORRECT ANSWERS WITH
RATIONALES .( What You Need to Know for 2026")
QUESTION
R-134a is a chlorine-free refrigerant.
a) True
b) False
CORRECT ANS: a) True
Expert Rationale
R-134a (1,1,1,2-Tetrafluoroethane) is a hydrofluorocarbon (HFC) refrigerant that does
not contain chlorine in its molecular structure (option True). Chlorine is the primary
element responsible for ozone depletion. Since R-134a lacks chlorine, it has an Ozone
Depletion Potential (ODP) of 0.0 and is considered an ozone-safe refrigerant. It was
introduced as a replacement for R-12 (CFC-12) in automotive air conditioning systems.
Its molecular formula is CH₂FCF₃, containing only carbon, hydrogen, and fluorine atoms.
Option False is incorrect because it would imply that R-134a contains chlorine, which it
does not.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Refrigerant Chemistry
MSC: EPA 609: Refrigerant Identification
QUESTION
The ozone layer absorbs and scatters ________ from the sun.
,a) Ultraviolet light
b) Infrared radiation
c) Visible light
d) X-rays
CORRECT ANS: a) Ultraviolet light
Expert Rationale
The ozone layer in the stratosphere absorbs and scatters the majority of the sun's
harmful ultraviolet (UV) radiation, specifically UV-B and UV-C (option a). This absorption
of UV light is what protects life on Earth from DNA damage, skin cancer, and other
harmful effects. The ozone molecule (O₃) absorbs UV radiation and undergoes
photodissociation, splitting into an oxygen molecule (O₂) and a free oxygen atom (O),
which can then recombine with O₂ to form more ozone, maintaining the ozone balance.
Option b is incorrect; infrared radiation is absorbed by greenhouse gases like CO₂ and
water vapor. Option c is incorrect; visible light is not absorbed by ozone. Option d is
incorrect; X-rays are absorbed by the upper atmosphere.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Ozone Layer
MSC: EPA 609: Ozone Depletion
QUESTION
For determining the Ozone Depletion Potential (ODP), which substance has been
assigned a factor of 1?
a) CFC-11
b) CFC-12
c) HCFC-22
d) HFC-134a
CORRECT ANS: a) CFC-11
,Expert Rationale
For determining the Ozone Depletion Potential (ODP), CFC-11 (trichlorofluoromethane)
has been assigned a reference factor of 1.0 (option a). All other substances are
measured relative to CFC-11's ODP. This means CFC-11 has the highest ozone depletion
potential among common refrigerants. CFC-12 has an ODP of 1.0 as well, but CFC-11 is
the standard reference. HCFC-22 has an ODP of 0.05, and HFC-134a has an ODP of 0.0.
Option b is incorrect; CFC-12 also has an ODP of 1.0, but CFC-11 is the reference. Option
c and d are incorrect; they have lower ODPs.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Ozone Depletion Potential
MSC: EPA 609: Ozone Depletion
QUESTION
A refillable refrigerant cylinder must not be filled above ______ of its full capacity.
a) 80%
b) 85%
c) 90%
d) 95%
CORRECT ANS: a) 80%
Expert Rationale
A refillable refrigerant cylinder must not be filled above 80% of its full capacity (option
a). This is a safety requirement mandated by the Department of Transportation (DOT).
The 80% fill limit allows for thermal expansion of the refrigerant as the temperature
rises, preventing the cylinder from becoming over-pressurized and potentially
exploding. The remaining 20% is called the "ullage" or expansion space.
, Option b, c, and d are incorrect; they exceed the maximum safe fill limit.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Refrigerant Cylinders
MSC: EPA 609: Refrigerant Handling
QUESTION
Ozone at ground level and at the stratosphere is a harmful pollutant.
a) True
b) False
CORRECT ANS: b) False
Expert Rationale
This statement is false (option False). Ozone at ground level (tropospheric ozone) is a
harmful pollutant and a primary component of smog. It is a respiratory irritant and can
damage plants and materials. However, ozone in the stratosphere is beneficial and
protective, as it absorbs harmful UV radiation. The statement incorrectly implies that
ozone at the stratosphere is harmful, which is not the case. Stratospheric ozone is
essential for life on Earth.
Option True is incorrect because it incorrectly describes stratospheric ozone as harmful.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Ozone Layer
MSC: EPA 609: Ozone Depletion
QUESTION
Each chlorine ion can destroy approximately ______ ozone molecules.
PRACTICE QUESTION AND CORRECT ANSWERS WITH
RATIONALES .( What You Need to Know for 2026")
QUESTION
R-134a is a chlorine-free refrigerant.
a) True
b) False
CORRECT ANS: a) True
Expert Rationale
R-134a (1,1,1,2-Tetrafluoroethane) is a hydrofluorocarbon (HFC) refrigerant that does
not contain chlorine in its molecular structure (option True). Chlorine is the primary
element responsible for ozone depletion. Since R-134a lacks chlorine, it has an Ozone
Depletion Potential (ODP) of 0.0 and is considered an ozone-safe refrigerant. It was
introduced as a replacement for R-12 (CFC-12) in automotive air conditioning systems.
Its molecular formula is CH₂FCF₃, containing only carbon, hydrogen, and fluorine atoms.
Option False is incorrect because it would imply that R-134a contains chlorine, which it
does not.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Refrigerant Chemistry
MSC: EPA 609: Refrigerant Identification
QUESTION
The ozone layer absorbs and scatters ________ from the sun.
,a) Ultraviolet light
b) Infrared radiation
c) Visible light
d) X-rays
CORRECT ANS: a) Ultraviolet light
Expert Rationale
The ozone layer in the stratosphere absorbs and scatters the majority of the sun's
harmful ultraviolet (UV) radiation, specifically UV-B and UV-C (option a). This absorption
of UV light is what protects life on Earth from DNA damage, skin cancer, and other
harmful effects. The ozone molecule (O₃) absorbs UV radiation and undergoes
photodissociation, splitting into an oxygen molecule (O₂) and a free oxygen atom (O),
which can then recombine with O₂ to form more ozone, maintaining the ozone balance.
Option b is incorrect; infrared radiation is absorbed by greenhouse gases like CO₂ and
water vapor. Option c is incorrect; visible light is not absorbed by ozone. Option d is
incorrect; X-rays are absorbed by the upper atmosphere.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Ozone Layer
MSC: EPA 609: Ozone Depletion
QUESTION
For determining the Ozone Depletion Potential (ODP), which substance has been
assigned a factor of 1?
a) CFC-11
b) CFC-12
c) HCFC-22
d) HFC-134a
CORRECT ANS: a) CFC-11
,Expert Rationale
For determining the Ozone Depletion Potential (ODP), CFC-11 (trichlorofluoromethane)
has been assigned a reference factor of 1.0 (option a). All other substances are
measured relative to CFC-11's ODP. This means CFC-11 has the highest ozone depletion
potential among common refrigerants. CFC-12 has an ODP of 1.0 as well, but CFC-11 is
the standard reference. HCFC-22 has an ODP of 0.05, and HFC-134a has an ODP of 0.0.
Option b is incorrect; CFC-12 also has an ODP of 1.0, but CFC-11 is the reference. Option
c and d are incorrect; they have lower ODPs.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Ozone Depletion Potential
MSC: EPA 609: Ozone Depletion
QUESTION
A refillable refrigerant cylinder must not be filled above ______ of its full capacity.
a) 80%
b) 85%
c) 90%
d) 95%
CORRECT ANS: a) 80%
Expert Rationale
A refillable refrigerant cylinder must not be filled above 80% of its full capacity (option
a). This is a safety requirement mandated by the Department of Transportation (DOT).
The 80% fill limit allows for thermal expansion of the refrigerant as the temperature
rises, preventing the cylinder from becoming over-pressurized and potentially
exploding. The remaining 20% is called the "ullage" or expansion space.
, Option b, c, and d are incorrect; they exceed the maximum safe fill limit.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Refrigerant Cylinders
MSC: EPA 609: Refrigerant Handling
QUESTION
Ozone at ground level and at the stratosphere is a harmful pollutant.
a) True
b) False
CORRECT ANS: b) False
Expert Rationale
This statement is false (option False). Ozone at ground level (tropospheric ozone) is a
harmful pollutant and a primary component of smog. It is a respiratory irritant and can
damage plants and materials. However, ozone in the stratosphere is beneficial and
protective, as it absorbs harmful UV radiation. The statement incorrectly implies that
ozone at the stratosphere is harmful, which is not the case. Stratospheric ozone is
essential for life on Earth.
Option True is incorrect because it incorrectly describes stratospheric ozone as harmful.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Ozone Layer
MSC: EPA 609: Ozone Depletion
QUESTION
Each chlorine ion can destroy approximately ______ ozone molecules.
