Question

1. what powers the sun?

the intense gravity of the sun crushes gas molecules together, which creates friction that produces heat.
nearly a quarter of the sun is made of helium. the 4 atoms in the nucleus fuse together and cause a nuclear reaction.
the sun is made mostly of flammable hydrogen gas that is in a constant process of ignition.
in the suns interior, nuclear fusion occurs when hydrogen molecules are fused into helium. the byproduct of the process produces the energy that powers the sun

Explanation:

The Sun is powered by nuclear fusion in its core. Hydrogen nuclei (protons) fuse to form helium. This process releases a huge amount of energy. Let's analyze each option:

• Option 1: Friction due to gravity is not the main source. The Sun's energy comes from nuclear processes, not just friction from gravity - crushed gas.
• Option 2: Helium is a product of hydrogen fusion in the Sun. But it's the hydrogen - to - helium fusion (not helium atoms fusing) that is the primary energy - producing process.
• Option 3: The Sun is not a "fire" in the traditional sense of a chemical ignition of hydrogen. It's a nuclear process.
• Option 4: In the Sun's interior, nuclear fusion occurs when hydrogen nuclei (not molecules, since in the core it's ionized) are fused into helium. The mass - defect in this process is converted into energy according to \(E = mc^{2}\), and this energy powers the Sun.

Answer:

In the Sun’s interior, nuclear fusion occurs when hydrogen molecules are fused into helium. The byproduct of the process produces the energy that powers the Sun.