What determines how a star develops after the red gaint stage in its cycle?
what two things can happen in the life of a massive star after it passes from the supernova star?

After the red giant stage in its cycle, depending on its mass would determine how the star will end up. For stars greater than 1 solar mass but less than 2 solar masses, the hydrogen burning shell consumes its way outward leaving behind more helium ash. As helium piles up, the core becomes bigger and then contracts. By contracting, it becomes warmer to the point that the electrons degenerate. From gas, it will then become liquid becoming incompressible and further contraction stops.

d.) circle motion requires a force to give it a centripetal acceleration.

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.