Younger stars have more heavy elements because
a. old stars destroy heavy elements as they age.
b. young stars burn their nuclear fuels faster.
c. the heavy elements were made in previous generations of stars.
d. heavy elements haven't had time to settle to the core of these younger stars.
e. all of these
C
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What part of a comet points most directly away from the Sun?
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A. 23 N/C B. zero C. 45 N/C D. 90 N/C E. 110 N/C
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