ASVAB Practice Test

What are the two main gases that make up stars?

1. Carbondioxide and Nitrogen

2. Hydrogen and Carbon

3. Hydrogen and Helium

4. Oxygen and Nitrogen

The correct answer is: Carbondioxide and Nitrogen

The primary components of stars are hydrogen and helium. Hydrogen is the most abundant element in the universe, serving as the fundamental fuel for nuclear fusion processes that take place in stars, generating energy and producing helium in the process. Helium is the second most abundant element formed from these fusion reactions, and it plays a crucial role in the lifecycle of stars. The other options list gases that are not the main constituents of stars. Carbon dioxide, nitrogen, and oxygen are found in the universe, but they make up a much smaller proportion of stellar composition compared to hydrogen and helium. While carbon is present in stars as a product of fusion in later stages of stellar evolution, it is not one of the foundational gases that make up stars primarily.