we presently consider the universe to be a matter dominated. In this stage the n
ID: 233505 • Letter: W
Question
we presently consider the universe to be a matter dominated. In this stage the number of photons
a. vastly outnumber the number of particles
b. is vastly outnumbered by the number of particles
c. is greatly outnumbered by the number of particles, but it is less than the number of particles Plus anti-particles
d. is close to be equal to the number of particles
very hot stars have weak hydrogen spectral lines. Why is this?
a. the Stars contain very little hydrogen
b. the hydrogen in the atmospheres of these stars is combined into molecules, and these have different Spectra
c. the electrons in the hydrogen atoms in the stars are all in their lowest energy levels, and they cannot radiate from these levels
d. the hydrogen atoms in the stars are mostly ionized and hence cannot radiate
white dwarfs are not included in the Luminosity classification because they are
a. not yet active Stars they have not yet begun nuclear reactions
b. no longer producing energy by nuclear reactions
c. no longer radiating energy away
d. too small
Explanation / Answer
Q 1. we presently consider the universe to be a matter dominated. In this stage the number of photons
Ans b. is vastly outnumbered by the number of particles
Q 2. very hot stars have weak hydrogen spectral lines. Why is this?
Ans. d. the hydrogen atoms in the stars are mostly ionized and hence cannot radiate
Q 3. white dwarfs are not included in the Luminosity classification because they are
Ans. a. not yet active Stars they have not yet begun nuclear reactions
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