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100
Suppose you find a rock that contains 10 micrograms of radioactive potassium-40, which has a half-life of 1.25 billion years. By measuring the amount of its decay product present in the rock, you conclude that there must have been 80 micrograms of potassium-40 when the rock solidified. How old is the rock?
3.75 billion years.
100
Many meteorites appear to have formed very early in the solar system's history. How do these meteorites support our theory about how the terrestrial planets formed?
The meteorites appearance and composition is just what we'd expect if metal and rock condensed and accreted as our theory suggests.
100
Which of the following is not a line of evidence supporting the hypothesis that our moon formed as a result of a giant impact?
the pacific ocean appears to be a larger crater- probably the one made by the giant impact.
100
according to our modern science, which of the following best explains why the vast majority of the mass of our solar system consists of hydrogen and helium gas?
hydrogen and helium are the most common elements throughout the universe, because they were the only elements present when the universe was young.
100
according to our present theory of solar system formation, how did earth end up with enough water to make oceans?
the water was brought to the forming Earth by planetesimals that accreted beyond the orbit of Mars.
200
According to our present theory of solar system formation, which of the following statements about the growth of terrestrial and jovian planets is not true?
the jovian planets began from plantesimals made only of ice, while the terrestrial planets began from planetesimals made only of rock and metal.
200
The region of our solar system between mercury and mars has very few asteroids, while the region between mars and Jupiter has many asteroids. based on what you have learned, what is the most likely explanation for the lack of asteroids between mercury and mars?
there were very few planetary leftovers in this region, because most of the solid material was accreted by the terrestrial planets as the planets formed.
200
what is the primary reason that astronomers suspect that some jovian moons were captured into their current orbits?
some moons have orbits that are "backwards" or highly inclined to their planet's equator.
200
about 2% of our solar nebula consisted of elements besides hydrogen and helium. however, the very first generation of stay systems in the universe probably consisted only of hydrogen and helium. which of the following statements is most likely to have been true about these first-generation star systems?
there were no comets or asteroids in these first-generation star systems.
200
according to our present theory of solar system formation, which of the following objects now reside quite far from the place where they formed originally?
oort cloud comets
300
what is the primary basis upon which we divide the ingredients of the solar nebula into four categories?
the temperatures at which various materials will condense from gaseous form to solid form.
300
according to our theory of solar system formation, which law best explains why the central regions of the solar nebula got hotter as the nebula shrank in size?
the law of conservation of energy.
300
which of the following best explains why we can rule out the idea that planets are usually formed by near-collisions between stars?
stellar near-collisions are far too rare to explain all the planets now known to orbit nearby stars.
300
according to our theory of solar system formation, which law best explains why the solar nebula spun faster as it shrank in size?
the law of conservation of angular momentum.
300
how do scientists determine the age of the solar system?
radiometric dating of meteorites
400
why are terrestrial planets denser than jovian planets.
only dense materials could condense in the inner solar nebula.
400
you discover an impact crater that is 10 kilometers across. which of the following can you conclude?
it was created by the impact of an object about 1 kilometer across.
400
the choices below describe four hypothetical planets. which one would you expect to have the most features of erosion?
size: same as venus. Distance from sun: same as mars. rotation rate: once every 25 hours.
400
recent evidence suggests that mars once had a global magnetic field. assuming this is true, which of the following could explain why mars today lacks a global magnetic field like that of earth?
mars's interior has cooled so much its molten core layer no longer undergoes convection.
400
which of the following most likely explains why venus does not have a global magnetic field like earth?
its rotation is too slow.
500
which internal heat source still generates heat within the terrestrial worlds today?
heat from radioactive decay
500
the choices below describe four hypothetical planets. which one's surface would you expect to be most crowded with impact craters?
size: same as the moon distance from sun: same as mars rotation rate: once every 10 days.
500
which of the following is the underlying reason why venus has so little wind erosion?
its slow rotation
500
based on all we know about the terrestrial worlds, what single factor appears to play the most important role in a terrestrial planet's geological destiny?
its size
500
which of the following is not generally true of all the terrestrial world lithospheres?
the lithosphere is broken into a set of large plates that float upon the softer rock below.
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