When was the first confirmed exoplanet discovered?
A) Shortly after the invention of the telescope, in the early 1600s
B) In prehistoric times
C) Around 350 BC, by the Ancient Greeks
D) Early in the 21st century
E) Near the end of the 20th century
E
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What will halt the collapsing Sun's core once its fuel has been exhausted?
A) the inability of electrons to enter into neighboring electrons quantum state B) outward thermal pressure C) random quantum fluctuations D) the shift from fusion to fission nuclear reactions
The mean free path of a molecule is 
m in an ideal gas at standard temperature and pressure. What is the mean free path when the pressure of the gas is doubled and the temperature is constant?
A. 
B. 
C. 
D. 
E. 
According to the theory of cosmic inflation, during a brief early "inflationary period," the universe
A) expanded at lightspeed. B) expanded at a speed that exceeded lightspeed. C) expanded at a speed that was only slightly slower than lightspeed. D) quickly became far more densely filled with matter. E) quickly became far more densely filled with energy.
A current element (length = 1.0 cm) lies along the x axis with its center at x = 0 and carries a 20-A current in the positive x direction. Consider only the field of this current element and decide which combination of the following statements is correct. 1 . The field at (0, 0, 1.0 m) is in the positive z direction. 2 . The field at (0, 1.0 m, 0) is in the negative y direction. 3 . The field at
(1.0 m, 0, 0) is zero. 4 . The field at (0, 0, 1.0 m) is in the negative y direction. a. 3 and 4 b. 1 and 3 c. 2 and 4 d. 1 and 2 e. None of these