When considering whether the density of the universe is above or below the critical density, what needs to be included in the measurement of density?
A) ordinary matter
B) ordinary matter and dark matter
C) ordinary matter, neutrinos, gravity waves and electromagnetic energy
D) ordinary matter, dark matter and electromagnetic energy
E) ordinary matter, dark matter, neutrinos, gravity waves, electromagnetic energy and dark energy
E
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When we see a half Moon in the sky, the lines between Earth, Moon, and Sun
A) are equal in length. B) are parallel to one another. C) form a right triangle. D) all of the above
When an electron de-excites from the third quantum level to the second, and then to the ground state, two photons are emitted
The sum of the emitted frequencies equals the frequency of the single photon that would be emitted if de-excitation were from the third to A) the second level. B) the ground state. C) any other level. D) none of the above
The region around Earth where the magnetic field traps charged particles is the
A) ozone layer. B) exosphere. C) Van Allen Radiation Belts. D) corona. E) aurora borealis and australis.
Deep trenches in the ocean mark places where
A) one plate slides under another, returning older crust to the mantle. B) plates pull apart, leaving great rifts in the crust. C) hot mantle material rises upward and spreads sideways, pushing the plates apart. D) plates push together, creating ocean mountain chains. E) plates slip sideways relative to one another.