The extreme size of volcanoes on Mars indicates that
a. Mars has a much thicker crust than Earth.
b. water once flowed in streams on Mars.
c. large moving plates have not formed on Mars.
d. a and c
e. a, b, and c
Question 2Starburst galaxies
a. contain a large number of very young stars, but very little evidence of gas clouds.
b. contain a large number of very old stars and almost no gas or dust.
c. are often associated with a galaxy that is colliding with another galaxy.
d. are common in rich clusters.
e. are composed of filaments and voids.
Question 3____ is a very long and deep canyon on Mars.
a. Valles Marineris
b. Ishtar Terra
c. Tharsis Bulge
d. Lobate Scarp
e. Phobos
Question 4Observations of galaxies and clusters of galaxies indicate that about ____ percent of the matteruniverse is dark matter.
a. 5
b. 25
c. 35
d. 45
e. 95
Question 5Mars has a sufficient mass and a low enough temperature that water molecules could exist in its atmosphere as vapor. One reason Mars' atmosphere does not contain a significant amount of water vapor is that
a. Mars formed in a part of the solar nebula that lacked oxygen.
b. Mars formed in a part of the solar nebula that lacked hydrogen.
c. All of the water vapor was released in the impact that formed Deimos.
d. Ultraviolet radiation breaks the water molecule into less massive particles that can escape.
e. The water molecule combines readily with chlorine to form hydrochloric acid.
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