Question

Which of the following statements about stages of nuclear burning (i.e., first-stage hydrogen burning, second-stage helium burning, etc.) in a massive star is not true?
A) As each stage ends, the core shrinks further.
B) Each successive stage of fusion requires higher temperatures than the previous stages.
C) Each successive stage lasts for approximately the same amount of time.
D) Each successive stage creates an element with a higher atomic weight.

Answer 1

Answer:

C) Each successive stage lasts for approximately the same amount of time.

Explanation:

Nuclear burning is a series of nuclear processes through which a star gets its energy. The energy within a star is due to nuclear fusion of lighter elements (hydrogen) into more massive element (helium), with a release of a large amount of energy due to the conversion of some of the mass into energy. Each stage leads to a loss of some of the mass which is converted into energy (option A is valid).

The fusion of four hydrogen atoms into one helium atom means that there is a creation of element with a higher atomic weight (option D is valid), and the energy output of each stage exceeds its energy input, meaning that each stage will require a higher temperature than its previous stages (option B is valid).