UCLA ASTRO 3 FINAL EXAM ACTUAL 2025/2026 QUESTIONS AND 100% CORRECT ANSWERS

UCLA ASTRO 3 FINAL EXAM ACTUAL 2025/2026 QUESTIONS AND 100% CORRECT ANSWERS How does a 1.2-solar-mass white dwarf compare to a 0.9-solar-mass white dwarf? Select one: a. It has a larger radius. b. It has a higher surface temperature. c. It has a smaller radius. d. It has a lower surface temperature. e. It is supported by neutron, rather than electron, degeneracy pressure. - Answer -c. It has a smaller radius. Compared to the star it evolved from, a white dwarf is Select one: a. hotter and brigher b. hotter and dimmer c. cooler and brighterd. cooler and dimmer e. the same temperature - Answer -b. hotter and dimmer Nuclear fusion proceeds in stars towards heavier and heavier elements. At what element does this nucleosynthetic chain stop? Select one: a. Hydrogen b. Helium c. Carbon d. Silicon e. Iron - Answer -e. Iron What is the ultimate fate of an isolated white dwarf? Select one: a. It will cool down and become a cold black dwarf. b. As gravity overwhelms the electron degeneracy pressure, it will explode as a nova. c. As gravity overwhelms the electron degeneracy pressure, it will explode as a supernova. d. As gravity overwhelms the electron degeneracy pressure, it will become a neutron star.e. The electron degeneracy pressure will eventually overwhelm gravity and the white dwarf will slowly evaporate. - Answer -a. It will cool down and become a cold black dwarf. After a massive-star supernova, what is left behind? Select one: a. always a white dwarf b. always a neutron star c. always a black hole d. either a white dwarf or a neutron star e. either a neutron star or a black hole - Answer -e. either a neutron star or a black hole The thermal pressure of a gas depends on Select one: a. density only. b. temperature only. c. density and temperature. d. composition. e. gravity. - Answer -c. density and temperature