If the Universe is closed and finite, then
a. the Universe will expand forever.
b. the Universe has a center.
c. the Universe has an edge.
d. None of the other choices are correct.
Question 2A planetary nebula is an example of a star no longer in hydrostatic equilibrium.
a. True
b. False
Indicate whether the statement is true or false
Question 3If the Universe is closed, then its age will be
a. less than two-thirds of 1/H.
b. more than two-thirds of 1/H.
c. equal to 1/H.
d. equal to H squared.
e. equal to the square-root of H.
Question 4When an aging massive star generates an iron core, the iron cannot fuse and thus the star cannot support its weight outside the core. The star is no longer in hydrostatic equilibrium and collapses, forming a supernova.
a. True
b. False
Indicate whether the statement is true or false
Question 5If gravity alone acts to retard the expansion and nothing acts to accelerate it, the Universe is said to be closed if I. gravity is strong enough to stop the expansion in a finite time. II. the density of the Universe is less than the critical density. III. the Universe is finite.
a. I & II
b. I & III
c. II & III
d. I, I, & III
e. None of the other choices are correct.
Question 6The spectra of Type II supernova contain no hydrogen lines.
a. True
b. False
Indicate whether the statement is true or false
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