Natural Science CLEP Prep Practice Exam

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Prepare for the CLEP Natural Science Exam with our comprehensive study materials and practice questions. Test your knowledge and ace the exam by mastering key concepts.

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

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What is the most abundant gas in Earth's atmosphere?

Helium
Hydrogen
Nitrogen
Oxygen

The correct answer is: Nitrogen

Nitrogen is the most abundant gas in Earth's atmosphere, making up about 78% of the air we breathe. Helium and hydrogen are both significantly less abundant, with helium making up less than 1% and hydrogen making up less than 0.00005%. Oxygen is the second most abundant gas in Earth's atmosphere, making up approximately 21%.