1.which is a characteristic of nuclear fission?

-releases nonradioactive waste only
-involves the collision of two nuclei
releases small amounts of energy compared to -fossil fuels
-involves the splitting of an atom into two or more fragments

2.both nuclear fusion and nuclear fission reactions

-release radioactive waste.
-involve the splitting of atoms.
-are utilized in nuclear power plants.
-release large amounts of energy.

3.which type of reaction does this diagram represent? (see attachment)

Here, I believe are the correct solutions:

1. A characteristic of nuclear fission basically involves the splitting of an atom into 2 or more fragments, whether they be particles or unstable nuclei.

2. Both nuclear fission and nuclear fission reactions are utilized in nuclear power plants.

3. The diagram showcases a series of nuclear fission reactions occurring which shows a chain reaction, in which a nuclei is bombarded with a particle producing other nuclei and particles that will affect them and so on.

Yes it would be a physical change.