Theorists are divided concerning the origin of the Moon. Somehypothesize that the Moon was formed in the same way as were the planets in theinner solar system (Mercury, Venus, Mars, and Earth)—from planet-formingmaterials in the presolar nebula. But, unlike the cores of the inner planets,the Moon’s core contains little or no iron, while the typical planet-formingmaterials were quite rich in iron. Other theorists propose that the Moon wasripped out of the Earth’s rocky mantle by the Earth’s collision with anotherlarge celestial body after much of the Earth’s iron fell to its core. Oneproblem with the collision hypothesis is the question of how a satellite formedin this way could have settled into the nearly circular orbit that the Moon hastoday. Fortunately, the collision hypothesis is testable. If it is true, themantlerocks of the Moon and the Earth should be the same geochemically.1. The primary purpose of the passage is to
(A) present two hypotheses concerning the origin of the Moon
(B)discuss the strengths and weaknesses of the collision hypothesisconcerning the origin of the Moon
(C)propose that hypotheses concerning the Moon’s origin be tested
(D) argue that the Moon could not have been formed out of the typicalplanet-forming materials of the presolar nebula
(E) describe one reason why the Moon’s geochemical makeup shouldresemble that of the Earth
2. According to the passage, Mars and the Earth are similar in whichof the following ways?I. Their satellites were formed by collisions with other celestialbodies.II. Their cores contain iron.III. They were formed from the presolar nebula.
(A) III only
(B) I and II only
(C) I and III only
(D) II and III only
(E) I, II, and III
3. The author implies that a nearly circular orbit isunlikely for a satellite that
(A) circles one of the inner planets
(B) is deficient in iron
(C) is different from its planet geochemically
(D) was formed by a collision between two celestialbodies
(E) was formed out of the planet-forming materials in the presolarnebula
4. Which of the following, if true, would be most likely to make itdifficult to verify the collision hypothesis in the manner suggested by theauthor?
(A) The Moon’s core and mantlerock are almost inactivegeologically.
(B) The mantlerock of the Earth has changed in composition since theformation of the Moon, while the mantlerock of the Moon has remained chemicallyinert.
(C) Much of the Earth’s iron fell to the Earth’s core long before theformation of the Moon, after which the Earth’s mantlerock remained unchanged.
(D) Certain of the Earth’s elements, such as platinum, gold, andiridium, followed iron to the Earth’s core.
(E) The mantlerock of the Moon contains elements such as platinum,gold, and iridium.
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