#1
Which gas was likely absent in Earth's early atmosphere?
Oxygen
ExplanationOxygen was likely absent due to volcanic outgassing.
#2
What is the primary component of Earth's atmosphere by volume?
Nitrogen
ExplanationNitrogen is the primary component of Earth's atmosphere.
#3
Which layer of Earth's atmosphere is closest to the planet's surface?
Troposphere
ExplanationThe troposphere is the layer closest to Earth's surface.
#4
What is the main source of atmospheric oxygen today?
Photosynthesis by plants
ExplanationPhotosynthesis by plants is the main source of atmospheric oxygen.
#5
Which layer of Earth's atmosphere contains the ozone layer?
Stratosphere
ExplanationThe ozone layer is found in the stratosphere.
#6
Which gas is most abundant in Earth's atmosphere after nitrogen and oxygen?
Argon
ExplanationArgon is the most abundant gas after nitrogen and oxygen.
#7
What process contributed to the formation of oxygen in Earth's atmosphere?
Photosynthesis
ExplanationPhotosynthesis by early life forms contributed to oxygen formation.
#8
Which era saw a significant rise in oxygen levels in Earth's atmosphere?
Proterozoic
ExplanationThe Proterozoic era saw a significant rise in oxygen levels.
#9
What is the primary function of the ozone layer in Earth's atmosphere?
To absorb ultraviolet radiation
ExplanationThe ozone layer absorbs harmful ultraviolet radiation.
#10
What event likely led to the formation of Earth's early atmosphere?
Outgassing from volcanoes
ExplanationOutgassing from volcanoes likely formed Earth's early atmosphere.
#11
Which gas is considered a greenhouse gas in Earth's atmosphere?
Carbon dioxide
ExplanationCarbon dioxide is a significant greenhouse gas.
#12
Which geological era marks the beginning of significant oxygen accumulation in Earth's atmosphere?
Proterozoic
ExplanationThe Proterozoic era marks the beginning of significant oxygen accumulation.
#13
Which scientist is credited with proposing the Gaia hypothesis, which suggests that Earth functions as a self-regulating system?
James Lovelock
ExplanationJames Lovelock proposed the Gaia hypothesis.
#14
What is the name of the event that led to the mass extinction of dinosaurs, changing Earth's atmosphere significantly?
Cretaceous-Paleogene (K-Pg) extinction event
ExplanationThe K-Pg extinction event led to significant atmospheric changes.
#15
Which event is believed to have caused the 'Snowball Earth' period, leading to dramatic changes in Earth's atmosphere?
Extreme glaciation
ExplanationExtreme glaciation caused the 'Snowball Earth' period.