Final answer:
A typical star, such as our Sun, begins to die once it exhausts its supply of hydrogen. This leads to a decrease in internal pressure and the collapse of the star. Fusion of helium takes place, but at a lower rate, until that is also exhausted, resulting in the final stages of a star's life.
Step-by-step explanation:
A typical star, such as our Sun, begins to die once it exhausts its supply of hydrogen. Hydrogen is the main fuel source for stars and is converted into helium through nuclear fusion reactions. Once the hydrogen in the star's core is used up, the star's internal pressure decreases and gravity causes it to collapse. This collapse leads to the fusion of helium, which produces a new flow of energy but at a much lower rate than hydrogen fusion. Eventually, even the fusion of helium is exhausted, leading to the final stages of a star's life.