Exam-style question
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Which of the following best explains why massive stars evolve more quickly off the main sequence than low‑mass stars?.
- A.They have lower core temperatures, so fusion is slower.
- B.They have larger radii, so they burn less fuel.
- C.They fuse hydrogen at a higher rate, exhausting fuel faster.
- D.They lose mass more slowly, keeping them on the main sequence longer.
Model answer
What a good answer should say
- They fuse hydrogen at a higher rate, exhausting fuel faster.
Explanation
Why this works
Higher mass stars have higher core pressures and temperatures, leading to a much faster hydrogen fusion rate. Consequently they consume their nuclear fuel more quickly and leave the main sequence sooner than low‑mass stars.
Common mistake
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