Question

which process that takes place in stars produces heavier elements from lighter elements?
radioactive decay
fusion
chemical reaction
fission

Explanation:

• Radioactive decay: It is a process where an unstable atomic nucleus loses energy by emitting radiation. It does not produce heavier elements from lighter ones in stars.
• Fusion: In stars, under high - temperature and high - pressure conditions, lighter atomic nuclei (such as hydrogen nuclei) combine to form heavier nuclei (such as helium nuclei). This is the process that builds up heavier elements from lighter ones in stars.
• Chemical reaction: Chemical reactions involve the rearrangement of electrons in atoms to form new chemical compounds. They do not change the nuclei of atoms to form heavier elements from lighter ones in the context of stars.
• Fission: It is a process where a heavy nucleus splits into lighter nuclei. This is the opposite of what is required (forming heavier from lighter) in the context of the question about stars.

Answer:

fusion