The cosmic background radiation comes from a time
a. when protons and neutrons were first formed.
b. when the big bang first began to expand.
c. during the inflationary period.
d. when gamma rays had enough energy to destroy nuclei.
e. when electrons began to recombine with nuclei to form atoms.
e
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A gravitationally bound universe, with omega greater than 1.0, will expand forever
Indicate whether the statement is true or false
An electron is known to be confined to a region of width 0.10 nm
What is an approximate value for the least kinetic energy it could have, in electron-volts? (h = 6.626 × 10-34 J ? s, 1 eV = 1.60 × 10-19 J, (melectron = 9.11 × 10-31 kg) A) 3.8 eV B) 1.1 eV C) 0.88 eV D) 17 eV E) 8.8 eV
Approximately what proportion of people in the United States believe we have been visited by extraterrestrials?
A) around 33% or a third B) about 50% or a half C) less than 1% D) more than 90%
At 96° F the saturation density of air is 0.04 kg/m3 . If the weather report says the relative humidity is 90 % when the temperature is 96°F, the humidity is
a. 10 % b. 0.9 c. 0.004 kg/m3 d. 0.036 kg/m3 e. 0.04 kg/m3