Answer:
1. A star of uniform composition from center to surface; it contains hydrogen but has no nuclear reactions going on in the core.
2. A star that is fusing hydrogen to form helium in its core.
3. A star that has no nuclear reactions going on in the core but is fusing hydrogen to form helium in a shell around the core.
4. A star that is fusing helium to carbon in the core and hydrogen to helium in a shell around the core.
5. A star with no nuclear reactions going on in the core, which is made primarily of carbon and oxygen.
