How does a red giant become a white dwarf?

Hint: A red giant is formed from a main sequence star and after that white dwarf is formed from it. The both red giant and white dwarf are different in terms of their sizes and intensity of light they produce or emit.

Complete answer:
A Red Giant star is a star which is about to lose its life and is in the last stage of Stellar Evolution. Hydrogen and helium are the two most important components that make up all the stars. Most of the stars in the universe we get to see are original sequence stars. They are 3 to 8 times large as compared to the sun. They burn through the hydrogen in its core. Over its life, the outward pressure of fusion has balanced the inward pressure of gravity. Once the fusion stops, the gravity takes the lead and compresses the star. The star becomes smaller and tighter. Because of this phenomenon, temperature increases to such an extent that helium is able to fuse into carbon. This occurrence leads to burning of the star and is known as red giant.
If a red giant star does not have a sufficient mass to generate temperature which is required to fuse carbon, then an inert layer of carbon dioxide and oxygen will form at the centre. The outer layer will be removed and the core which will be left is known as white dwarf.

Note:One of the differences between red giant and white dwarf is that-Red giant is bigger in size and white dwarf is comparatively much smaller. Another contrasting point is that the Red giant is much more luminous than White dwarf.