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MCQBeginnerCosmology & the Early Universe
USAAAO — 2021 First Round
Question 29
Given that the redshift of cosmic microwave background (CMB) is 1100, what was the temperature of the Universe when photon decoupled from matter and neutral hydrogen started to get formed? The present temperature of the CMB is 2.73 K.
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Source
USAAAO 2021 First Round. Question text, choices, and answer were transcribed from the official USAAAO exam and solutions PDFs.