WGU C165 Integrated Physical Sciences
– Earth & Sky OA 300 Practice Questions
& Answers (2026 Update) 300 Practice
Questions & Answers (2026 Update)
EXAM STRUCTURE & INSTRUCTIONS
Course: WGU C165 Integrated Physical Sciences
Assessment: Objective Assessment (OA) - Earth & Sky Domain
Content Areas:
Astronomy & The Solar System (25%)
Earth's Structure & Plate Tectonics (25%)
Earth's Atmosphere & Weather (20%)
Earth's Water & Oceans (15%)
Geologic Time & Earth's History (15%)
Instructions: Select the single best answer for each question. Questions with
"Select all that apply" require marking all correct options.
DOMAIN I: Astronomy & The Solar System (Questions 1-75)
1. What is the Milky Way?
A) A type of star
B) The galaxy that contains our solar system
C) A constellation visible from Earth
,D) A nebula where stars are born
✅ Correct Answer: B - The galaxy that contains our solar system
📖 Rationale: The Milky Way is a barred spiral galaxy containing our solar
system. It is one of billions of galaxies in the universe.
2. What is the approximate age of the universe according to current scientific
understanding?
A) 4.5 billion years
B) 13.8 billion years
C) 100 billion years
D) 1 trillion years
✅ Correct Answer: B - 13.8 billion years
📖 Rationale: Based on cosmic microwave background radiation and
expansion rate measurements, the universe is approximately 13.8 billion
years old.
3. What is the Big Bang Theory?
A) The explosion of a massive star
B) The theory that the universe began from an extremely hot, dense
singularity and has been expanding ever since
C) The formation of our solar system
D) The collision of two galaxies
✅ Correct Answer: B - The theory that the universe began from an extremely
hot, dense singularity and has been expanding ever since
📖 Rationale: The Big Bang Theory is the leading scientific explanation for
the origin of the universe.
4. Which of the following provides evidence for the Big Bang Theory? (Select
all that apply)
A) Cosmic microwave background radiation
B) Redshift of distant galaxies (Hubble's Law)
,C) Abundance of light elements (hydrogen, helium)
D) The presence of black holes
✅ Correct Answer: A, B, C - Cosmic microwave background radiation,
redshift of distant galaxies, abundance of light elements
📖 Rationale: These three lines of evidence strongly support the Big Bang
Theory. Black holes are not direct evidence.
5. What is Hubble's Law?
A) The farther away a galaxy is, the faster it is moving away from us
B) The closer a galaxy is, the faster it is moving toward us
C) All galaxies are moving toward a single point
D) Galaxies do not move relative to each other
✅ Correct Answer: A - The farther away a galaxy is, the faster it is moving
away from us
📖 Rationale: Hubble's Law demonstrates the expanding universe; redshift
increases with distance.
6. What is a light-year?
A) The time it takes light to travel from the Sun to Earth
B) The distance light travels in one year
C) The brightness of a star
D) The age of a star
✅ Correct Answer: B - The distance light travels in one year
📖 Rationale: A light-year is a unit of distance, not time, equal to about 5.88
trillion miles.
7. How long does it take light from the Sun to reach Earth?
A) 1 second
B) 8 minutes
C) 1 hour
, D) 1 day
✅ Correct Answer: B - 8 minutes
📖 Rationale: Light travels from the Sun to Earth in approximately 8 minutes
and 20 seconds.
8. What is the Sun primarily made of?
A) Iron and nickel
B) Hydrogen and helium
C) Oxygen and carbon
D) Nitrogen and argon
✅ Correct Answer: B - Hydrogen and helium
📖 Rationale: The Sun is about 73% hydrogen and 25% helium by mass, with
trace amounts of other elements.
9. What process produces energy in the Sun?
A) Chemical combustion
B) Nuclear fission
C) Nuclear fusion
D) Radioactive decay
✅ Correct Answer: C - Nuclear fusion
📖 Rationale: In the Sun's core, hydrogen nuclei fuse to form helium,
releasing enormous energy.
10. What is the correct order of the planets from the Sun outward?
A) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
B) Mercury, Venus, Earth, Mars, Saturn, Jupiter, Uranus, Neptune
C) Venus, Mercury, Earth, Mars, Jupiter, Saturn, Neptune, Uranus
D) Earth, Mars, Mercury, Venus, Jupiter, Saturn, Uranus, Neptune
✅ Correct Answer: A - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus,
– Earth & Sky OA 300 Practice Questions
& Answers (2026 Update) 300 Practice
Questions & Answers (2026 Update)
EXAM STRUCTURE & INSTRUCTIONS
Course: WGU C165 Integrated Physical Sciences
Assessment: Objective Assessment (OA) - Earth & Sky Domain
Content Areas:
Astronomy & The Solar System (25%)
Earth's Structure & Plate Tectonics (25%)
Earth's Atmosphere & Weather (20%)
Earth's Water & Oceans (15%)
Geologic Time & Earth's History (15%)
Instructions: Select the single best answer for each question. Questions with
"Select all that apply" require marking all correct options.
DOMAIN I: Astronomy & The Solar System (Questions 1-75)
1. What is the Milky Way?
A) A type of star
B) The galaxy that contains our solar system
C) A constellation visible from Earth
,D) A nebula where stars are born
✅ Correct Answer: B - The galaxy that contains our solar system
📖 Rationale: The Milky Way is a barred spiral galaxy containing our solar
system. It is one of billions of galaxies in the universe.
2. What is the approximate age of the universe according to current scientific
understanding?
A) 4.5 billion years
B) 13.8 billion years
C) 100 billion years
D) 1 trillion years
✅ Correct Answer: B - 13.8 billion years
📖 Rationale: Based on cosmic microwave background radiation and
expansion rate measurements, the universe is approximately 13.8 billion
years old.
3. What is the Big Bang Theory?
A) The explosion of a massive star
B) The theory that the universe began from an extremely hot, dense
singularity and has been expanding ever since
C) The formation of our solar system
D) The collision of two galaxies
✅ Correct Answer: B - The theory that the universe began from an extremely
hot, dense singularity and has been expanding ever since
📖 Rationale: The Big Bang Theory is the leading scientific explanation for
the origin of the universe.
4. Which of the following provides evidence for the Big Bang Theory? (Select
all that apply)
A) Cosmic microwave background radiation
B) Redshift of distant galaxies (Hubble's Law)
,C) Abundance of light elements (hydrogen, helium)
D) The presence of black holes
✅ Correct Answer: A, B, C - Cosmic microwave background radiation,
redshift of distant galaxies, abundance of light elements
📖 Rationale: These three lines of evidence strongly support the Big Bang
Theory. Black holes are not direct evidence.
5. What is Hubble's Law?
A) The farther away a galaxy is, the faster it is moving away from us
B) The closer a galaxy is, the faster it is moving toward us
C) All galaxies are moving toward a single point
D) Galaxies do not move relative to each other
✅ Correct Answer: A - The farther away a galaxy is, the faster it is moving
away from us
📖 Rationale: Hubble's Law demonstrates the expanding universe; redshift
increases with distance.
6. What is a light-year?
A) The time it takes light to travel from the Sun to Earth
B) The distance light travels in one year
C) The brightness of a star
D) The age of a star
✅ Correct Answer: B - The distance light travels in one year
📖 Rationale: A light-year is a unit of distance, not time, equal to about 5.88
trillion miles.
7. How long does it take light from the Sun to reach Earth?
A) 1 second
B) 8 minutes
C) 1 hour
, D) 1 day
✅ Correct Answer: B - 8 minutes
📖 Rationale: Light travels from the Sun to Earth in approximately 8 minutes
and 20 seconds.
8. What is the Sun primarily made of?
A) Iron and nickel
B) Hydrogen and helium
C) Oxygen and carbon
D) Nitrogen and argon
✅ Correct Answer: B - Hydrogen and helium
📖 Rationale: The Sun is about 73% hydrogen and 25% helium by mass, with
trace amounts of other elements.
9. What process produces energy in the Sun?
A) Chemical combustion
B) Nuclear fission
C) Nuclear fusion
D) Radioactive decay
✅ Correct Answer: C - Nuclear fusion
📖 Rationale: In the Sun's core, hydrogen nuclei fuse to form helium,
releasing enormous energy.
10. What is the correct order of the planets from the Sun outward?
A) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
B) Mercury, Venus, Earth, Mars, Saturn, Jupiter, Uranus, Neptune
C) Venus, Mercury, Earth, Mars, Jupiter, Saturn, Neptune, Uranus
D) Earth, Mars, Mercury, Venus, Jupiter, Saturn, Uranus, Neptune
✅ Correct Answer: A - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus,
