1st: Fusion (it happens in the core of the sun)
2nd: Both (is the key to understanding why and how energy is released in nuclear reactions)
3rd: Fission (this kind of plants uses nuclear reactors where fission occurs)
4th: Fission (is a reaction in which the nucleus of an atom splits into two or more smaller nuclei)
5th: Fusion (is the process by which two or more atomic nuclei join together to form a single heavier nucleus and large amounts of energy)
6th: Fission (subdivision of a heavy atomic nucleus, such as that of uranium or plutonium)
7th: Fusion
Answer:
1-FUSION
2-BOTH
3-FISSION
4-FISSION
5-FUSION
6-FISSION
7-FUSION