Final answer:
The mass of the Sun consists of approximately 75% hydrogen. This proportion respects the fact that hydrogen atoms are lighter and more numerous, while the less abundant helium atoms have a greater mass, affecting the overall mass composition of the Sun.
Step-by-step explanation:
The mass of the sun is composed of about 75% hydrogen. This is because, in terms of atoms, about 92% of the Sun's atoms are hydrogen, but when it comes to mass, hydrogen only accounts for approximately 73% due to its lighter atomic weight compared to helium, the second most abundant element in the Sun. Helium atoms are roughly four times as massive as hydrogen atoms, so while they are much less numerous, they make up a significant fraction of the Sun's total mass.
Hydrogen, being the lightest and most abundant element in the universe, forms about 70%-75% of the universe by mass and a similar percentage of the Sun's mass. In stars like our Sun, hydrogen serves as the fuel for nuclear fusion reactions that produce an immense amount of energy. The process predominantly involves the fusion of hydrogen atoms into helium at extremely high temperatures and pressures at the core of the Sun.
Throughout its life, the Sun converts a considerable amount of hydrogen into helium and loses a fraction of its mass due to the mass-energy equivalence principle outlined by Einstein's equation, E = mc². This fusion process powers the Sun and is responsible for the sunlight and warmth that we experience on Earth.