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Home Q & A Board Science-Related Homework Help Physics
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doit_the_clown doit_the_clown
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7 years ago
How is cool, neutral hydrogen gas, H I, detected in the spiral arms of galaxies?
A)   By the absorption of infrared radiation from extragalactic sources
B)   By its Balmer line emissions
C)   By its 21-cm line radio emissions
D)   By its ultraviolet, Lyman , hydrogen line emissions
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Discovering the Universe

Discovering the Universe


Edition: 7th
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Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.

Albert Einstein
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discovererdiscoverer
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7 years ago
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doit_the_clown Author
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7 years ago
You make an excellent tutor!
einstein
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Yesterday
Helped a lot
ethom947
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2 hours ago
Brilliant ツ
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