What are the main constituents of Earth's atmosphere?
A. hydrogen and helium
B. carbon dioxide and water vapor
C. nitrogen and oxygen
D. methane and ozone
Answer: C
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One of the main causes of slow surface evolution is the:
A) depletion of ozone layer. B) erosion due to moving air and water. C) heat released from infalling matter. D) heavy bombardment in the early Solar System.
We see two stars separated by one degree on the celestial sphere. What can we infer about these stars?
A) They are very close together in space. B) They have similar luminosities. C) They rise and set at about the same time. D) They were born about the same time.
What fraction of the original uranium-235 should be left after 3.5 billion years?
A) 1/2 B) 1/4 C) 1/8 D) 1/32 E) 1/64
A piece of iron sinks to the bottom of a lake where the pressure is 21 times what it is at the surface of the lake. Which statement best describes what happens to the volume of that piece of iron?
A) Its volume increases slightly. B) Its volume decreases slightly. C) There has been no change in the volume of the iron. D) Its volume becomes 1/21 what it was at the surface. E) Its volume becomes 21 times greater than at the surface.