1. A main sequence star is any star that is fusing hydrogen in its core and has a stable balance of outward pressure from core nuclear fusion and gravitational forces pushing inward. An example is our sun
2. A giant star is any star having a relatively large radius for its mass and temperature
3. Supergiant stars form out of massive main-sequence stars that have run out of hydrogen in their cores.
4. When the pressure drops low enough in a massive star, gravity suddenly takes over and the star collapses in just seconds.
5. Super novas are so powerful they could create new atomic nuclei
I hope this helps:)
