Which type of star spends the longest time as a protostar?
A) G star B) M star C) O star D) B star
B
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The wave front shown at the left for light in air reaches the plane boundary between air and two transparent mediums with n1 = 1.5 and n2 = 3.00, respectively.
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Which diagram below correctly illustrates the wave front after it has entered the two mediums at the right?
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A. A B. B C. C D. D E. E
An X-ray photon has more energy than a visible photon
Indicate whether the statement is true or false
Most astronomers agree to interpret ________ Law to mean that the present day universe is expanding
Fill in the blank(s) with correct word
The ocean crust
A) becomes progressively younger away from the mid-ocean ridges. B) is the same age worldwide. C) becomes progressively older away from the mid-ocean ridge. D) ranges in age, the oldest ocean crust is in the Atlantic and the youngest is in the Arctic.