The universe formed Helium nuclei in a process called nucleosynthesis. At that time, what fraction of the mass was converted to Helium nuclei (2 protons and 2 neutrons)?
A. 2 percent
B. 50 percent
C. 25 percent
D. 99 percent
E. 1 percent
Answer: C. 25 percent
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What is the result of the Greenhouse effect on the surface environment of Venus?
A) It has little or no effect. B) Its effect is about the same as on Earth. C) It has reduced the surface temperature by about 30 degrees Celsius. D) It has raised the surface temperature by hundreds of degrees Celsius. E) It causes the surface temperature of Venus to become hotter than the Sun.
Force on a Moving Charge: At a particular instant, a proton moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is
A. zero. B. upward. C. toward the north. D. toward the south. E. downward.
Suppose the star Sirius were moved to a distance 7 times closer to Earth than it is now. How would its parallax angle change?
A) It would stay the same. B) It would get smaller. C) It would get larger.
Process of Science: Climate models can match the historical record of the global temperature on Earth and conclude that human's increase of atmospheric CO2 is responsible for global warming. How might you test this conclusion?
What will be an ideal response?