An irregular galaxy contains mostly
a. lower-main sequence stars and giants.
b. upper main sequence stars and giants.
c. upper main sequence stars and gas and dust.
d. upper and lower main sequence stars and gas and dust.
e. white dwarfs and supergiants.
Question 2Slow surface evolution on the moon is limited to
a. low density masses of rock rising from the interior.
b. low level meteorite impacts.
c. moonquakes disturbing the surface features.
d. motion along a network of small faults.
e. all of the above
Question 3A spiral (S or SB) galaxy contains
a. mostly lower-main sequence stars and giants.
b. mostly upper main sequence stars and giants.
c. mostly upper main sequence stars and gas and dust.
d. upper and lower main sequence stars and gas and dust.
e. mostly white dwarfs and supergiants.
Question 4Why would a decrease in the density of the ozone layer create a public health concern?
a. The greenhouse effect would not be as efficient and the temperature of Earth would decrease.
b. The greenhouse effect would be more efficient and the temperature of Earth would increase.
c. Plant life would no longer have the ozone it needs for photosynthesis to create chlorophyll.
d. Ultraviolet radiation from the sun would bombard Earth.
e. none of the above
Question 5An E galaxy contains
a. mostly lower-main sequence stars and giants.
b. mostly upper main sequence stars and giants.
c. mostly upper main sequence stars and gas and dust.
d. roughly equal numbers of upper and lower main sequence stars.
e. mostly white dwarfs and supergiants.
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