SKILLCAT EPA 608 EXAM — COMPLETE STUDY GUIDE
All 244 Questions with Verified Answers & Detailed Rationales
(2026/2027)
Question 1
1. What is the chemical formula of an ozone molecule?
A) O₂
B) O₃
C) CO₂
D) ClO
Answer
Answer B: ) O₃
,Rationale
Ozone is a molecule composed of three oxygen atoms (O₃). It is
found primarily in the stratosphere where it forms the protective
ozone layer that absorbs harmful ultraviolet radiation from the sun.
---
Question 2
2. Where is the majority of Earth's ozone located?
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
Answer
Answer B: ) Stratosphere
Rationale
The majority of Earth's ozone is located in the stratosphere,
approximately 10-30 miles above the Earth's surface. This layer is
crucial for absorbing harmful UV rays. ---
,Question 3
3. Which of the following is the primary source of chlorine in the
stratosphere?
A) Volcanic eruptions
B) Ocean evaporation
C) Emissions of refrigerants (CFCs and HCFCs)
D) Forest fires
Answer
Answer C: ) Emissions of refrigerants (CFCs and HCFCs)
Rationale
Emissions of refrigerants (CFCs and HCFCs) are the primary source
of chlorine in the stratosphere. While volcanoes do contribute some
chlorine, the amount is small compared to CFC emissions. ---
Question 4
4. Which molecule is primarily responsible for destroying the
ozone layer?
A) Oxygen
B) Nitrogen
C) Chlorine
, D) Hydrogen
Answer
Answer C: ) Chlorine
Rationale
Chlorine is the primary molecule responsible for destroying the
ozone layer. When CFCs reach the stratosphere, UV radiation
breaks them apart, releasing chlorine atoms. ---
Question 5
5. One molecule of chlorine can destroy how many molecules of
ozone?
A) 10
B) 1,000
C) 10,000
D) 100,000
Answer
Answer D: ) 100,000
All 244 Questions with Verified Answers & Detailed Rationales
(2026/2027)
Question 1
1. What is the chemical formula of an ozone molecule?
A) O₂
B) O₃
C) CO₂
D) ClO
Answer
Answer B: ) O₃
,Rationale
Ozone is a molecule composed of three oxygen atoms (O₃). It is
found primarily in the stratosphere where it forms the protective
ozone layer that absorbs harmful ultraviolet radiation from the sun.
---
Question 2
2. Where is the majority of Earth's ozone located?
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
Answer
Answer B: ) Stratosphere
Rationale
The majority of Earth's ozone is located in the stratosphere,
approximately 10-30 miles above the Earth's surface. This layer is
crucial for absorbing harmful UV rays. ---
,Question 3
3. Which of the following is the primary source of chlorine in the
stratosphere?
A) Volcanic eruptions
B) Ocean evaporation
C) Emissions of refrigerants (CFCs and HCFCs)
D) Forest fires
Answer
Answer C: ) Emissions of refrigerants (CFCs and HCFCs)
Rationale
Emissions of refrigerants (CFCs and HCFCs) are the primary source
of chlorine in the stratosphere. While volcanoes do contribute some
chlorine, the amount is small compared to CFC emissions. ---
Question 4
4. Which molecule is primarily responsible for destroying the
ozone layer?
A) Oxygen
B) Nitrogen
C) Chlorine
, D) Hydrogen
Answer
Answer C: ) Chlorine
Rationale
Chlorine is the primary molecule responsible for destroying the
ozone layer. When CFCs reach the stratosphere, UV radiation
breaks them apart, releasing chlorine atoms. ---
Question 5
5. One molecule of chlorine can destroy how many molecules of
ozone?
A) 10
B) 1,000
C) 10,000
D) 100,000
Answer
Answer D: ) 100,000
