1.   The molecule that contributes most to the greenhouse effect on Earth is 
        A. methane. 
        B. ozone. 
        C. carbon dioxide. 
        D. water. 

2.  The molecule that does NOT contribute to the greenhouse effect on Earth 
     is 
        A. methane. 
        B. carbon dioxide. 
        C. nitrogen. 
        D. water. 

3.  The Moon has many more craters than Earth because 
        A. it shielded Earth from collisions. 
        B. asteroids cannot penetrate Earth's atmosphere. 
        C. Earth's are all beneath the ocean. 
        D. it has no erosion or geological activity to erase craters. 

4.  Why do we think the climate of Mars has changed? 
        A. The atmosphere is currently rich in methane. 
        B. Old river beds exist, but no water flows there today. 
        C. Fossil trees found by the Viking spacecraft show it was once hot 
           and wet. 
        D. Its mean density is between that of Earth and the Jovian planets. 

5.  The principle reason that the terrestrial planets have different geology 
     is 
        A. rotation rate. 
        B. distance from the Sun. 
        C. thickness of the atmosphere. 
        D. planetary mass. 

6.  The greenhouse effect occurs because 
        A. Visible radiation is blocked by the atmosphere. 
        B. Ultraviolet radiation is blocked by the atmosphere. 
        C. Ultraviolet radiation is blocked by the ozone layer. 
        D. Infrared radiation is blocked by the atmosphere. 

7.  Compared to its neighboring planets, Mercury, Venus, and Mars, the 
     surface of the Earth is relatively young. This youthful appearance 
     results from 
        A. the Earth being the most recently formed of these planets. 
        B. the Earth having the largest Moon of all of these planets. 
        C. tectonic activity still shaping the surface of the Earth. 
        D. the fact that few major impacts ever occur on the Earth. 
        E. the Earth is furthest from the Sun. 

8.  Planets are spherical while asteroids are irregularly shaped because 
        A. asteroids can not be irregular in shape. 
        B. gravity dominates over material strength in planets. 
        C. material strength dominates over gravity in planets. 
        D. gravity dominates over material strength in asteroids. 

9.  The "runaway greenhouse effect" occurred on which planet? 
        A. Mercury 
        B. Earth 
        C. Venus 
        D. Mars 

10.   The composition of solid objects in the outer solar system differs from 
     those inside the frost line in that 
        A. they are composed of ices as well as rocks and metals. 
        B. they are composed of rock. 
        C. they are composed of ices instead of rock. 
        D. there is no difference. 

11.   Which of the following types of observations must be done above the 
     Earth's atmosphere? 
        A. Optical 
        B. All of these can be done on the earth. 
        C. Radio 
        D. X-ray 

12.  If all the asteroids in the asteroid belt were assembled into a planet, 
     it would have a mass 
        A. About the same mass as the Earth. 
        B. Much greater than Jupiter's mass. 
        C. Much less than that of the Earth. 
        D. About the same mass as Jupiter. 

13.  Which of the following is NOT one of Kirchoff's Laws? 
        A. A cool medium obscuring a continuum source results in an 
           absorption line spectrum. 
        B. Hot, diffuse gas produces an emission line spectrum. 
        C. Hot, dense objects emit a continuous spectrum. 
        D. The peak wavelength of light emitted by a thermal source 
           decreases with increasing temperature. 

14.  As the solar nebula collapsed, 
        A. it gradually flattened to a disk-shaped cloud. 
        B. the amount of angular momentum remained the same. 
        C. all of the other answers. 
        D. the bulk of the gas ended up in the Sun. 

15.  The map of solar system in order of distance from the sun would read 
        A. terrestrial planets, asteroid belt, jovian planets, Kuiper belt. 
        B. terrestrial planets, jovian planets, asteroid belt, Kuiper belt. 
        C. jovian planets, asteroid belt, terrestrial planets, Kuiper belt. 
        D. terrestrial planets, asteroid belt, Kuiper belt, jovian planets. 

16.  Why are the terrestrial planets so much smaller than the Jovian ones? 
        A. The Sun has pulled material off of them. 
        B. They spin so fast they flung off most of their original matter 
           which has ended up in the comet cloud. 
        C. Near the Sun, only hard to melt substances which are rare 
           compared to hydrogen could condense. Thus, there was less material 
           to build them. 
        D. They are formed from highly compressible material such as hydrogen 
           and helium so they could be squeezed to a very small size. 


   1. D.
   2. C.
   3. D.
   4. B.
   5. D.
   6. D.
   7. C.
   8. B.
   9. C.
  10. A.
  11. D.
  12. C.
  13. D.
  14. C.
  15. A.
  16. C.