Which pair of elements are described as the most common in stars?

Which pair of elements are described as the most common in stars?

• A. Helium and Hydrogen
• B. Oxygen and Nitrogen
• C. Neon and Argon
• D. Carbon and Helium

Answer: (A)

Hydrogen and helium dominate the makeup of stars. Most of a star’s mass is hydrogen, with helium as the next most abundant element. This reflects how stars form from gas clouds rich in hydrogen and helium, and how fusion in the core converts hydrogen into helium while the overall bulk still remains primarily these two elements. Because “most common” refers to what makes up the vast majority of stellar matter, hydrogen and helium are the correct pairing. Heavier elements like oxygen, nitrogen, neon, argon, and carbon occur in much smaller amounts, so they aren’t described as the most common.

Hydrogen and helium dominate the makeup of stars. Most of a star’s mass is hydrogen, with helium as the next most abundant element. This reflects how stars form from gas clouds rich in hydrogen and helium, and how fusion in the core converts hydrogen into helium while the overall bulk still remains primarily these two elements. Because “most common” refers to what makes up the vast majority of stellar matter, hydrogen and helium are the correct pairing. Heavier elements like oxygen, nitrogen, neon, argon, and carbon occur in much smaller amounts, so they aren’t described as the most common.