Question

how are elements formed in nature?

Answer 1

Hydrogen has been with us since the beginning. Almost all of the helium, and a little bit of lithium and deuterium was formed by fusion in the first few minutes of the Big Bang. More helium and some light elements, like carbon, nitrogen, oxygen and silicon, are formed by fusion in bigger stars and ejected into the cosmos when the star dies. Still heaver elements are made in heavier stars, and ejected in novae. Elements heavier than iron are made only in supernova explosions.