12. Which star will leave the Main Sequence first?
a. Alpha Centauri A, because it is more massive
b. Alpha Centauri B, because it is less massive
c. they will both leave at the same time, because they were born together
d. there is no way to tell, because the stars are touching each other and exchanging mass

13. When does a protostar become a star?
a. when it begins to fuse hydrogen in its core
b. when its mass becomes greater than half a solar mass
c. when the peak of its spectrum moves into visible light
d. when the cloud of gas and dust around it is cleared away

14. Which phase in a low-mass star's evolution lasts longest?
a. protostar
b. Main Sequence
c. red giant
d. horizontal branch

15. What is the difference between a red giant and an asymptotic giant?
a. an asymptotic giant's interior is like a red giant's, but its surface is hotter, so it's not red
b. high-mass stars become red giants; low-mass stars become asymptotic giants
c. an asymptotic giant is a star that is traveling up the giant branch and will eventually become a red giant
d. a red giant has a degenerate helium core; an asymptotic giant has a degenerate carbon core

16. The Pleiades and the Hyades are two star clusters in the constellation of Taurus. The Pleiades has many bright blue stars but no bright red stars, and the Hyades has many bright red stars and few bright blue stars. What can we conclude?
a. the Pleiades is older than the Hyades
b. the Hyades is older than the Pleiades
c. the Pleiades is closer than the Hyades
d. the Hyades is closer than the Pleiades

17. Drs. Harden, Petrie, and Rozyczka discover a binary system consisting of a white dwarf of about 1.4 solar masses and a red giant of about 2 solar masses. They report that the red giant seems to be losing mass, which is going onto the white dwarf. What will happen to this system when the white dwarf exceeds the Chandrasekhar limit?
a. the white dwarf will collapse into a black hole
b. a Type I supernova
c. a Type II supernova
d. mass will start flowing back onto the red giant