Orbital electrons do not spiral into the atomic nucleus because of
1) electrical forces,
2) the wave nature of the electrons,
3) angular momentum,
4) the discreteness of energy levels,
5) quantum mechanical laws,
and the electrons have discrete radii from the nucleus because
6) the circumference of each orbit is an integral multiple of the electron wavelength.
7) electrical forces act over discrete distances.
8) energy levels themselves are discrete.
Answer: 2, 6
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Why are sunspots cooler than the surrounding solar surface?
A) They are regions where convection carries cooler material downward. B) Strong magnetic fields slow convection and prevent hot plasma from entering the region. C) Magnetic fields trap ionized gases that absorb light. D) There is less fusion occurring there. E) Magnetic fields lift material from the surface of the Sun, cooling off the material faster.
The internal energy of a monatomic ideal gas is equal to which of the following?
a. (3/2)PV b. (3/2)nT/V c. 3 T/P d. none of the above
How are wavelength, frequency, and energy related for photons of light?
A) Longer wavelength means lower frequency and lower energy. B) Longer wavelength means higher frequency and lower energy. C) Longer wavelength means higher frequency and higher energy. D) Longer wavelength means lower frequency and higher energy. E) There is no simple relationship because different photons travel at different speeds.
Recall that Hubble's law is written v = H0d, where v is the recession velocity of a galaxy located a distance d away from us, and H0 is Hubble's constant. Suppose H0 = 22 km/s/million light-years. How fast would a galaxy 1000 million light-years away be receding from us?
A) 22 km/s B) 22 million light-years/s C) 22,000 km/s D) 1000/22 km/s E) 0.22 times the speed of light