Why couldn't life have originated on the Moon or Mercury?
What will be an ideal response?
For life to begin, liquid water is needed. The Moon and Mercury are airless worlds, and water would boil away into space immediately.
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An atom that is excited
a. is also ionized. b. is an isotope. c. has had its electron moved to the lowest energy level. d. can emit a photon when the electron moves to a lower energy level. e. can emit a photon when the electron moves to a higher energy level.
Why did the solar nebula flatten into a disk?
A) The force of gravity pulled the material downward into a flat disk. B) It flattened as a natural consequence of collisions between particles in the nebula, changing random motions into more orderly ones. C) As the nebula cooled, the gas and dust settled onto a disk. D) The interstellar cloud from which the solar nebula formed was originally somewhat flat.
What is the best way to determine a galaxy's redshift?
A) Find the galaxy's apparent distance, and look up the redshift based on Hubble's Law. B) Find the color of the galaxy, and estimate its distance based on how red the galaxy is. C) Measure the magnitude of the galaxy, estimate its distance, and calculate its redshift using Hubble's Law. D) Take a spectrum of the galaxy, and measure the difference in wavelength of spectral lines from the wavelengths of those same lines as measured in the laboratory.
Photon Energy: A helium-neon laser emits light at 632.8 nm. If the laser emits 1.82 × 10-17 photons/second, what is its power output in mW? (c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s)
A. 57.2 mW B. 28.6 mW C. 37.2 mW D. 45.7 mW