Multiple Choice
We detect neutral gas in the interstellar medium by looking for radiation at 21 cm that arises when
A) an electron moves from the n = 1 to n = 2 state in a hydrogen atom.
B) an electron is ionized from a hydrogen atom.
C) carbon monoxide (CO) gas is excited by stellar radiation.
D) an electron's magnetic poles flip and align with the magnetic poles of a proton in a hydrogen atom.
E) an electron combines with a proton to make a hydrogen atom.
Correct Answer:
Verified
Correct Answer:
Verified
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