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In the Sun's proton-proton chain, how many hydrogen nuclei fuse to make one helium nucleus?

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  1. Four
  2. Two
  3. Twelve

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References

  1. Astronomy 2e, 16.2 Mass, Energy, and the Theory of Relativity openstax.org/books/astronomy-2e/pages/16-2-mass-energy-and-the-theory-of-relativity Checked 2026-10-10.

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