What are two variables that form larger and heavier elements than hydrogen and helium in starts?

fusion

A star's energy comes from combining light elements into heavier elements in a process known as fusion, or "nuclear burning". It is generally believed that most of the elements in the universe heavier than helium were created in stars when lighter nuclei fuse to make heavier nuclei.

Explanation:

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burning of wood and coal

explanation:

the panel also concluded there's a better than 95 percent probability that human-produced greenhouse gases such as carbon dioxide, methane and nitrous oxide have caused much of the observed increase in earth's temperatures over the past 50 years.

high growth (apex)