Question

The chain of fusion reactions, leading from hydrogen to helium, that powers main-sequence stars is called _____.

a) CNO cycle
b) Triple-alpha process
c) Proton-proton chain
d) Carbon fusion

Answer 1

The chain of fusion reactions is called the proton-proton chain. Larger stars undergo the triple-alpha process, and hotter stars use the CNO cycle.

Step-by-step explanation:

The chain of fusion reactions leading from hydrogen to helium that powers main-sequence stars is called the proton-proton chain or proton-proton cycle.

In stars that are larger and heavier than our sun, the dominant nuclear reaction is called the triple-alpha process. In this process, helium nuclei fuse to eventually form carbon.

In hotter stars, another set of reactions called the carbon-nitrogen-oxygen (CNO) cycle accomplishes the same net result. In the CNO cycle, carbon and hydrogen nuclei collide to form nitrogen, oxygen, and ultimately, helium.