What fraction of the mass of Earth is made up of the elements hydrogen and helium?
A) about 70%
B) 2%
C) much less than 1%
D) 98%

Question

Quizplus · Accepted Answer

Hydrogen and helium, despite being the most abundant elements in the universe, make up much less than 1% of the Earth's mass. This is because Earth's gravity is not strong enough to retain these light gases in its atmosphere, especially in the early stages of the planet's formation. Most of the Earth's mass is composed of heavier elements like oxygen, silicon, magnesium, and iron.

What Fraction of the Mass of Earth Is Made Up