Why isn't Earth's atmosphere mostly hydrogen?
A) Earth formed too close to the Sun for any planetesimals to have hydrogen.
B) All the hydrogen was blasted away during the early bombardment stage of the solar system.
C) Light gases such as hydrogen move faster than heavier gases and escape from Earth's gravitational field.
D) The hydrogen is frozen in the polar ice caps.
E) All the hydrogen reacted with oxygen and formed the oceans.
C
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What will you see with the following type of optic: Convex mirror
A. Image is smaller |
B. Image is the same |
C. Image is larger |
What is the approximate composition of the interstellar medium (by mass) in our region of the Milky Way?
A) 60% hydrogen, 40% helium B) 70% hydrogen, 28% helium, 2% heavier elements C) 70% hydrogen, 20% helium, 10% heavier elements D) 50% hydrogen, 48% helium, 2% heavier elements
You discover a binary star system in which one member is a15 solar mass main-sequence star and the other star is a 10 solar mass giant star. How do we believe that a star system such as this might have come to exist?
A) The two stars probably were once separate but became a binary when a close encounter allowed their mutual gravity to pull them together. B) Other than the very low odds of finding a system with two such massive stars, there is nothing surprising about the fact that such systems exist. C) The main-sequence star probably is a pulsating variable star and therefore appears to be less massive than it really is. D) Although both stars probably formed from the same clump of gas, the more massive one must have had its birth slowed so that it became a main-sequence star millions of years later than its less massive companion. E) The giant must once have been the more massive star but transferred some of its mass to its companion.
What happens to the cyclotron frequency of a charged particle if the radius of its path doubles?
A) It quadruples. B) It triples. C) It doubles. D) It halves. E) It does not change.