Astronomers have found the black hole at the center of the Milky Way has a mass of about ________ solar masses.
A. 4 hundred thousand
B. 4 million
C. 4 billion
D. 40
Answer: B
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we imagine the history of the universe compressed into one year, with the present as the stroke of midnight at the very end of that year, dinosaurs became extinct
A) about 6 months ago. B) about 3 weeks ago. C) yesterday morning. D) about an hour ago.
Refer to the figure above showing the abundance of elements in the galaxy relative to hydrogen. What is the general trend in elemental abundance?
A) Elements with more protons are less abundant. B) Elements with more protons are more abundant. C) Elements heavier than iron do not exist. D) Elements heavier than iron are relatively abundant. E) There is no apparent trend in the abundance of elements.
In the field induction credited to Maxwell, wires
A) can be insulated or non-insulated. B) are minimized. C) are not needed.
The Cambrian Explosion began approximately
A) 2.1 billion years ago B) 542 million years ago C) 1.2 billion years ago D) 65 million years ago