A supernova is the explosion of a star. Generally they are very massive stars that at the end of their life end up expelling all the material that was inside by means of a shock wave and that allows us to see the different layers that made it up.
There are different types of supernova that explode in different ways.
Type I are those that explode in a thermonuclear manner.
The type II are very massive stars that during their life maintain a balance of forces between the energy they produce, which is centrifugal, outwards, and the gravity that is a force towards the interior of the star.
They are relatively rare and difficult to detect events.
The importance of supernovae is that they allow us to measure the greatest distances within the universe.
To guess the % of each element in the supernovas I have used graphics of optical emission spectroscopy supernova that explain with examples how to recognize the type of supernovae and the elements in it according to the e.V of the different elements.