Final answer:
The correct option is a. New stars primarily consist of hydrogen and helium, with hydrogen serving as the main fuel for nuclear fusion. Stars evolve from simple compositions with no core reactions to complex stages where elements like helium, carbon, and oxygen are produced.
Step-by-step explanation:
The composition (fuel) of new stars is predominantly hydrogen and helium. Hydrogen, the lightest and most abundant element in the universe, makes up about 70% to 75% of the universe's mass. It serves as the main fuel for stars, undergoing fusion reactions in their cores. Helium is the second-most abundant element, constituting nearly a quarter of a star's mass.
Evolutionary Order of Stars
To arrange the stars based on their evolutionary stages, we consider the nuclear reactions occurring in their cores:
- B. A star of uniform composition with hydrogen but no nuclear reactions in the core (the earliest stage of stellar evolution).
- C. A star that is fusing hydrogen to form helium in its core (a main sequence star).
- E. A star with no nuclear reactions in the core but fusing hydrogen to form helium in a shell around the core (a red giant).
- D. A star that is fusing helium to carbon in the core and hydrogen to helium in a shell around the core (advanced red giant).
- A. A star with no nuclear reactions in the core, which is made primarily of carbon and oxygen (a white dwarf, the final evolutionary stage of a low to intermediate-mass star).