Which of the following best describes the primary composition of a typical white dwarf star?

• A. Hydrogen and helium nuclei
• B. Carbon and oxygen nuclei
• C. Iron nuclei
• D. Silicon and magnesium nuclei

Answer: (B)

Verified step by step guidance

1. Understand that a white dwarf star is the remnant core of a medium-sized star that has exhausted its nuclear fuel and shed its outer layers.
2. Recall that during the star's life, it fuses hydrogen into helium, then helium into heavier elements like carbon and oxygen, but it does not reach the stage of fusing elements heavier than oxygen in significant amounts.
3. Recognize that the core of a typical white dwarf is primarily composed of the elements produced by helium fusion, which are carbon and oxygen nuclei.
4. Note that hydrogen and helium nuclei are mostly found in the outer layers of stars or in less evolved stars, not in the dense core of a white dwarf.
5. Understand that iron, silicon, and magnesium nuclei are more typical of more massive stars or later stages of stellar evolution, such as supernova remnants, not typical white dwarfs.