Choose from the list below for the following questions.You may use a choice more than once.
-Which one is used by a main-sequence star of spectral type B2?
A)H fusion by the proton-proton chain
B)H fusion by the CNO cycle
C)helium fusion
D)matter-antimatter annihilation
E)gravitational contraction

Question

Quizplus · Accepted Answer

Main-sequence stars of spectral type B2 have high enough temperatures and densities to utilize the CNO (carbon-nitrogen-oxygen) cycle for hydrogen fusion in their cores.

Answer: C
 After the hydrogen fuel in a main-sequence star has been depleted, it will contract and heat up until it reaches a temperature and density sufficient for helium fusion to occur. This is the process that powers the next phase of the star's life cycle.

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