41.For a star of Sun-like mass, what the last stage : 1777248
41.For a star of Sun-like mass, what is the last stage of the nuclear fusion?
A.Hydrogen to helium.
B.Helium to carbon and oxygen.
C.Carbon to magnesium.
D.Fusion goes all the way up to iron.
42.What are the two longest stages in the life of a one solar mass star?
A.Protostar, pre-main sequence.
B.Protostar, white dwarf.
D.Main-sequence, white dwarf.
43.What nuclear fusion mechanism does an isolated white dwarf use to generate energy?
C.Triple alpha process
D.White dwarfs don't generate their own energy.
44.Stars that have ejected a planetary nebula eventually become
45.After what evolutionary stage does a star become a white dwarf?
46.Where are elements heavier than iron primarily produced?
47.The explosion of a supernova typically leaves behind
A.a planetary nebula.
B.a shell of hot, expanding gas with a white dwarf at the center.
C.a shell of hot, expanding gas with a pulsar at the center.
D.nothing is ever left behind.
48.The density of a neutron star is
A.about the same as that of a white dwarf.
B.about the same as that of the sun.
C.about the same as an atomic nucleus.
49.The ____________ of a black hole is the radius from a black hole at which the escape velocity is approximately equal to the speed of light.
50.Observations from the Compton Gamma Ray Observatory showed that gamma-ray bursters were located throughout the sky. This told us that
A.the bursts were not produced among stars in the disk of our galaxy.
B.the bursts were not produced among stars in the nuclear bulge of our galaxy.
C.the bursts are not associated with planets in our solar system
D.the bursts were not produced in our Sun
E.All of the above