When is/was gravitational contraction an important energy generation mechanism for the Sun?
A) It was important when the Sun was forming from a shrinking interstellar cloud of gas.
B) It is the primary energy generation mechanism in the Sun today.
C) It has played a role throughout the Sun's history, but it was most important right after nuclear fusion began in the Sun's core.
D) It is important during periods when the Sun is going from solar maximum to solar minimum.
A
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Stars much more luminous than the Sun have
A) narrower habitable zones, decreasing the odds of finding habitable planets and lifetimes too short for life to appear B) wider habitable zones, increasing the odds of finding habitable planets but lifetimes too short for life to appear C) narrower habitable zones, decreasing the odds of finding habitable planets but much longer lifetimes allowing life to appear and evolve D) wider habitable zones, increasing the odds of finding habitable planets and much longer lifetimes allowing life to appear and evolve
The Zeeman effect reveals the presence of strong magnetic fields by the splitting of spectral lines
Indicate whether the statement is true or false
A vessel containing 10 kg of water is left out where it evaporates. If the temperature remains constant at 20°C, what is the change in entropy (in kcal/K)? (The latent heat of vaporization at 20°C is 585 cal/g.)
a. 30 b. 10 c. 20 d. 40 e. 290
The diagram represents energy levels in a hydrogen atom. The labeled transitions (A through E) represent an electron moving between energy levels. Which labeled transition represents an electron that absorbs a photon with 10.2 eV of energy?
A) A B) B C) C D) D E) E