2. In the sun the dominant energy producing reaction involves putting (see p.126,127)

electrons together.
protons together.
photons together.
neutrinos together.

3. The energy produced by nuclear fusion in stars results from (see Helps & Hints)

mass being converted into energy.
the acceleration of protons.
the acceleration of hydrogen.
the strong magnetic fields produced in the core.

4. One of the important reasons for studying solar neutrinos is because they

carry information about the sun's core.
help the sun shine.
carry heat energy to the Earth.
help create nuclear fusion in the sun's core.

5. Which of the following best describes the solar neutrino problem?

neutrinos can not be detected
neutrinos are only theoretical, none have been found
fewer neutrinos are produced than can be accounted for by our theories
fewer neutrinos are detected than should be according to our theories

6. One very simple description of a main sequence star is:

a ball of gas balanced between the force of gravity pulling toward the center and energy from the core pushing out.
a ball of gas balanced between the force of gravity pushing out and energy from the core pulling inward.
a ball of gas balanced by the force of gravity pulling inward and the rotation which throws material outward.
a ball of gas balanced by inertia and the conversion of mass into energy in the core.

7. Most stars that have been studied are

much like our sun.
brighter than our sun.
main sequence stars.
larger than our sun.

8. Photons produced in the sun's core (see Helps & Hints)

take a million years to reach the photosphere (surface); neutrinos take weeks.
take a million years to reach the photosphere (surface); neutrinos take minutes.
may take several hundred thousand years to reach the photosphere; neutrinos take a few seconds.
may take several hundred thousand years to reach the photosphere; neutrinos take weeks.

9. More massive stars

produce energy slowly and are not very luminous.
produce more energy and are more luminous.
may or may not be very luminous depending on their composition.
have more gravity and therefore less energy flows out as light.

10. The upper limit for the mass of a star seems to be about (M_o= solar masses:see Helps & Hints)

100-150 M_o; a larger mass would cause them to explode
100-150 M_o; a larger mass would cause them to form Brown Holes.
20 M_o; a larger mass would cause them to collapse.
20 M_o; a larger mass would cause them to explode.

11. Choose the correct statement about Brown Dwarfs.

They fuse helium not hydrogen in their core and are abundant.
They fuse hydrogen in their core and are abundant.
They are smaller, more massive and abundant.
They have low temperatures and are hard to find.

12. Compared to smaller stars, massive stars use their fuel

much more efficiently and therefore have longer life spans.
much faster and therefore have shorter life spans.
more slowly and therefore have shorter life spans.
more slowly and therefore have longer life spans.

13. The life span of a main sequence star with 2 M_o and 14 times more luminous than the sun is less than

twice as long as the sun's life.
14 times longer than the sun's life.
14 times shorter than the sun's life.
6 times shorter than the sun's life.

14. As main sequence stars like the sun use up the hydrogen in their cores, (see Helps & Hints)

the core collapses and cools; the surface expands and cools.
the core expands and cools; the surface expands and cools.
the core collapses and heats up; the surface expands and cools.
the core expands and heats up; the surface expands and cools.

Lesson 12 "The Death of Stars"

15. At the end of a star's life, the battle between gravity and the outward internal pressure is

won by pressure.
won by gravity.
once again a balance between the two.
won by pressure in a white dwarf and by gravity in a neutron star.

16. When the sun becomes a red giant

life on Earth will move underground.
it will expand slightly.
some of the polar ice will melt.
Mercury and Venus will spiral into the sun.

17. Planetary nebula probably are caused by

hydrogen fusion in shells (layers) above the core.
helium fusion in shells (layers) above the core.
a hot carbon-oxygen core.
a very compact core.

18. A white dwarf is a

solid star about the size of Jupiter.
solid star about the size of the Earth.
very dense gas about the size of the Earth.
very dense star about the size of Jupiter.

19. The correct life cycle for the sun is thought to be

nebula - main sequence - planetary nebula - red giant - white dwarf.
main sequence - planetary nebula - red giant - white dwarf.
nebula - main sequence - red giant - planetary nebula - white dwarf.
main sequence - red giant- nova - white dwarf.

20. A white dwarf in a binary system can pull gas off from its companion. Choose the most likely result.

This causes a planetary nebula to form around the companion.
The companion often explodes creating a nova.
The companions core becomes exposed causing it to explode.
Gas builds up on the surface of the white dwarf until it becomes hot enough to fuse in a sudden explosion.

21. A Type I supernova occurs when a white dwarf accretes enough mass to cause

it to explode.
a large nuclear reaction on its surface.
it to collapse into a neutron star.
it to eject a planetary nebula.

22. A Type II supernova is created by the red supergiant of a massive star whose

iron core explodes
neutron core explodes.
iron core collapses.
neutron core collapses.

23. Choose the incorrect statement concerning Type II supernova.

Gases ejected from supernova explosions may help form new stars.
Nearby supernova events are rather rare, the last one occurred in 1987.
Large numbers of neutrinos are created.
All produce neutron stars.

24. Choose the incorrect statement concerning supernova in general:

During a supernova event the star may become millions of times brighter.
Most of the energy is released in the form of neutrinos.
Supernova shock waves are the only way that new stars are created.
Heavy elements like copper and nickel are created.

25. Which of the following spectral classes cannot form white dwarfs.

O
G
K
M

Prepared by: Mike Mitchell

Be sure to review your quizzes before taking the test.