Answer: I Hope This Helped :)
1. In the process of nuclear fusion, atoms are being combined to form a heavier nucleus. This process releases a large amount of energy and results in a slight decrease in the total mass of the nucleus. The mass that is lost in the fusion process is converted into energy, according to Einstein's famous equation E=mc^2, where E represents the energy released, m represents the mass that is lost, and c is the speed of light.
2. Energy is generated during nuclear fusion because the process involves the release of a large amount of energy in the form of photons (light particles) and subatomic particles, such as neutrons and alpha particles. This energy is released because the atomic nuclei are combining and forming a more stable, lower-energy nucleus.
3. The sun neither expands nor contracts in nuclear fusion because there is a delicate balance between the inward gravitational force and the outward pressure created by the energy released during fusion. As long as this balance is maintained, the sun will remain stable and not expand or contract significantly.
4. The light from the sun has changed over time because the nuclear fusion reactions that power the sun occur at different depths within the sun's core. As the sun ages and uses up its fuel, the fusion reactions move outward, which causes a change in the wavelengths of light that are emitted. This is why the sun's light has changed from being bluer in the past to being more yellowish-white in the present.