Microfossil evidence suggests that life
A) originated when the Earth formed 4.6 billion years ago
B) originated about 3.4 billion years ago
C) existed 3.85 billion years ago
D) existed and was well established by 3.4 to 3.5 billion years ago
D
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Which of the following specifications would allow you to precisely meet someone for an appointment?
A. meet me at my car B. meet me at my office, room 203 in Williams Hall on campus C. meet me at my office, room 203 in Williams Hall on campus at 2:30 PM D. meet me at my office E. meet me at 2:30 PM
X-rays from the Sun's corona
A) are absorbed in Earth's troposphere. B) are absorbed in Earth's thermosphere. C) cause meteor showers. D) break apart ozone in the stratosphere. E) generally reach Earth's surface.
Why are sunsets and sunrises red?
What will be an ideal response?
At atmospheric pressure, 45 moles of liquid helium are vaporized at its boiling point of 4.22 K. The heat of vaporization of helium, at atmospheric pressure, is 2.09 × 104 J/kg,
and the atomic weight of helium is 4.00 g/mol. The change in the entropy of the helium, as it vaporizes, is closest to A) 890 J/K. B) 14,000 J/K. C) 18,000 J/K. D) -9400 J/K. E) -14,000 J/K.