First Term Test

October 23 1996

Read all questions carefully. Each multiple choice question is worth one point. The last question is worth a total of eleven points, with the value of each part given in square [ ] brackets. If you have not already done so, write your name and student number onto the exam now.

  1. Carbon was made:
    1. In the big bang.
    2. In stars less massive than the sun.
    3. In stars more massive than the sun.
    4. On the surfaces of terrestrial planets.
  2. Carbon is different from nitrogen because
    1. Carbon typically has an atomic mass of 12, while nitrogen has an atomic mass of 14.
    2. A carbon nucleus has six protons, while a nitrogen nucleus has seven.
    3. Carbon has a different chemical nature than nitrogen.
    4. None of the above.
  3. Radioisotope dating works by:
    1. Measuring the half-life of unstable isotopes.
    2. Measuring the abundance of (ordinarily rare) decay products of unstable iosotpes.
    3. Measuring heat produced by the decay of unstable isotopes.
    4. Both (a) and (b).
  4. The solar system is
    1. A few thousand years old.
    2. A few million years old.
    3. A few billion (1,000,000,000=one billion) years old.
    4. Hundreds of billions of years old.
  5. The planets are believed to have formed out of:
    1. Gas pulled out of the sun by a passing star
    2. A dusty disk that fed the proto-sun.
    3. In interstellar space.
    4. None of the above.
  6. Jupiter has a massive hydrogen atmosphere. It was massive enough to capture this gas because:
    1. Jupiter formed in a region so hot that only refractory materials condensed out of the proto-planetary disk.
    2. Jupiter formed in a region cool enough that both refractory and volatile material condensed out of the proto-planetary disk.
    3. Jupiter formed in a region where there was a large amount of hydrogen.
    4. None of the above.
  7. Most of the angular momentum in the solar system is:
    1. Contained in the most massive body, the Sun.
    2. Contained in the terrestrial planets.
    3. Contained in the giant planets.
    4. Contained in Pluto.
  8. The satellite systems of the giant planets resemble the solar system. The spacing between moons increases as one moves out from the planet, the moons orbit in a plane and in the same sense as the rotation of the planet. Given that material formed of refractory elements is denser than material formed from volatile elements would you expect that the density of the moons:
    1. Increases with increasing distance from the planet.
    2. Decreases with increasing distance from the planet.
    3. Does not depend on distance from the planet.
  9. Most asteroids are found between: (an astronomical unit, or AU, is the mean distance between Earth and the Sun, 150,000,000km)
    1. 0.25-0.75 AU
    2. 2-4 AU
    3. 5-10 AU
    4. 10-15 AU
  10. The asteroid belt contains regions in semi-major axis where no asteroids are found and which are known as the Kirkwood gaps. These gaps are due to:
    1. The high temperature of the proto-planetary disk in these regions, which did not allow planetesimals to form.
    2. The passage of large bodies through the gaps early in the history of the solar system.
    3. Collisions between asteroids in these regions.
    4. Chaotic instabilities due to strong perturbations from Jupiter. These perturbations arise because of resonances between the orbital periods of bodies placed in the gaps and the orbital period of Jupiter.
  11. The albedos, or reflectivities of asteroids vary dramatically. High-albedo asteroids, which are believed to be contain large amounts of metals, are found in the inner portion of the asteroid belt, while low albedo, carbon and ice bearing asteroids are found further out. This is probably due to
    1. Dynamical evolution of the asteroid belt.
    2. The variation of temperature with distance in the solar nebula.
    3. The break up of a differentiated ``parent'' planet.
    4. None of the above.
  12. The elemental abundances in meteorites are very similar to those of the solar atmosphere (aside from volatiles such as H and He). This suggests that:
    1. The solar nebula was well mixed or homogeneous.
    2. The solar nebula was stratified rather than well mixed.
    3. Meteorites formed outside the solar system.
    4. None of the above.
  13. The large terrestrial planets are more geologically active than the smaller planets and moons because :
    1. Large bodies cool more rapidly than small bodies.
    2. Large bodies cool less rapidly than small bodies.
    3. Large bodies never reach the high temperatures that small bodies do.
    4. Large bodies do not form a lithosphere.
  14. The terrestrial planets and some moons of giant planets show evidence for heating due to:
    1. Accretion.
    2. Radioactive decay.
    3. Tidal stresses.
    4. All of the above.
  15. The surface of the Earth is very lightly cratered, while that of Mercury very heavily cratered. This is because:
    1. The Earth was not subject to such a heavy bombardment as Mercury, since it is not so close to the sun.
    2. The Earth's atmosphere protected it from falling bodies, while Mercury has no atmosphere.
    3. The Earth is larger than Mercury.
    4. None of the above.
  16. Meteorites are believed to come from:
    1. Asteroids.
    2. The moon.
    3. Outside the solar system.
    4. Both (a) and (b).
  17. Most meteorites belong to the class of:
    1. Stony meteorites.
    2. Iron meteorites.
    3. Stony-Iron meteorites.

Part 2

[3] Give evidence for your answer to question (4).

[2] Give evidence for your answer to question (15).

[3] Give evidence for your answer to question (16).

[3] Name and describe three mechanisms by which planets cool.

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