Newton's theory of universal gravitation states that every massive particle in the universe attracts every other massive particle with a force proportional to the mass of the particles and their proximity to one another. Consequently, cosmologists would expect that calculations based on this theory would yield an accurate measure of the mass in the universe; in fact, though, the total amount of observable matter in the universe does not contain enough mass to account for the organization of the universe into clusters of galaxies. To explain this discrepancy, cosmologists have developed the theory of "dark matter:" they postulate that the missing mass consists of elementary particles too small to be detected by electromagnetic radiation, and that these particles provide the mass necessary to hold the universe together. According to available evidence, these particles can only account for a maximum of 20 percent of the missing mass in the universe, yet their existence brings us one important step closer to solving the mystery of the missing matter.

According to the passage, which of the following factors is believed to help account for the missing mass in the universe?

A. Massive particles with a force proportional to the mass of the particles attract additional mass to the universe.
B. Tiny particles that are not currently observable by humans compose some of the missing mass.
C. "Dark matter" adheres to mass and causes it to expand. G
D. alaxies organize themselves into clusters to compensate for the lack of other mass in the universe.
E. The proximity of certain particles to each other forces an attraction that creates mass.



For the following question, consider each of the choices separately and select all that apply

The passage suggests that a massive particle would be most likely to attract another particle

❑ with a force related to the mass of each particle.
❑ at a distance related to the mass of each particle.
❑ by using an elementary particle as an intermediary.



Which one of the following statements, if true, would most weaken the argument?

A. While Country B has a regional airport, Country A has an international airport.
B. Country As newly elected government raised taxes with the goal of guaranteeing a more just distribution of wealth.
C. The type of coal always burned in Country A is different from the type of coal always burned in Country B.
D. Both Country A and Country B have been in a recession.
E. Agricultural production is also falling in Country A.