Before about 50,000 years after the Big Bang the universe was
A) radiation dominated.
B) quark dominated.
C) lepton dominated.
D) matter dominated.
E) dark energy dominated.
A
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A single slit of width 0.0300 mm is used to project a diffraction pattern of 500 nm light on a screen at a distance of 2.00 m from the slit. What angle does the central maximum subtend as measured from the slit?
a. 
b. 
c. 
d. 
e. 
Which of the following objects may have organic particles on its surface as a result of the interaction of sunlight with methane in its upper atmosphere?
a. Io b. Titan c. Mimas d. Ganymede e. Callisto
What do astronomers mean by light pollution?
A) Light pollution refers to pollution caused by light industry as opposed to heavy industry. B) Light pollution refers to harmful gases emitted by common street lights. C) Light pollution refers to light used for human activities that brightens the sky and hinders astronomical observations. D) Light pollution refers to the lights that must be used inside major observatories and that make it difficult for astronomers' eyes to adapt to darkness. E) Light pollution is another name for sunlight, which makes it impossible to see stars in the daytime.
The temperature of the photosphere of the Sun is closest to:
A. 600000 K B. 100 K C. 107 K D. 106 K E. 6000 K