What makes up the interstellar medium?
A) O and B stars
B) open clusters
C) K and M stars
D) gas and dust
E) all of the above
D
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What is an atom made of?
A.) Photons and electrons. B.) Photons, gravitons, and strange quarks. C.) Protons, neutrons, and electrons. D.) Positrons and electrons. E.) Neutrons, photons, and W bosons.
A chemoautotroph gets its energy from
A) chemical reactions and its carbon from its environment B) the Sun and its carbon from other organisms C) chemical reactions and its carbon from other organisms D) the Sun and its carbon from its environment
A baseball is located at the surface of the earth. Which statements about it are correct? (There may be more than one correct choice.)
A) The earth exerts a much greater gravitational force on the ball than the ball exerts on the earth. B) The ball exerts a greater gravitational force on the earth than the earth exerts on the ball. C) The gravitational force on the ball due to the earth is exactly the same as the gravitational force on the earth due to the ball. D) The gravitational force on the ball is independent of the mass of the ball. E) The gravitational force on the ball is independent of the mass of the earth.
For which of the following reasons is production of ethanol unwise?
a. Pollutants aren't significantly reduced. b. It takes twice as much fossil-fuel energy to produce ethanol than the ethanol that is produced supplies. c. It can drive costs of corn higher. d. All of the above.