49 Which of the following is one of the challenges engineers and workers had to face during the construction of the Qinghai-Tibet Railroad?
(A) Travelers from Beijing may suffer altitude sickness in Lhasa.
(B) The idea of a train trip is not as appealing as that of air travel.
(C) The tourism industry is impossible on the snow-covered permafrost.
(D) The railroad track may become bent or curved if frozen ground melts.

45 (A) so (B) if (C) as (D) when

46 What is the main purpose of this passage? (A) To compare two famous Chinese railroads. (B) To explain a health hazard at high altitudes. (C) To detail the process of constructing a railroad. (D) To persuade travelers to take a train trip to Tibet.

47 Which of the following statements about the Qinghai-Tibet Railroad is NOT true according to this passage? (A) It runs across high altitudes. (B) It connects Lhasa with Qinghai. (C) It causes the permafrost to melt. (D) It marks an amazing engineering victory.

48 What does the word "permafrost" in the second paragraph most likely mean? (A) A hard shiny metal that exists in the ground. (B) A layer of soil and rock that stays icy forever. (C) A place where water from a river falls down over a cliff. (D) A straight surface that has one side higher than the other.

50 Which of the following statements can be inferred from this passage? (A) The Qinghai-Tibet Railroad is a record holder in terms of the total length of its track. (B) The completion of the Qinghai-Tibet Railroad is likely to enhance Tibet's tourism industry. (C) Thousands of engineers died of altitude sickness while building the Qinghai-Tibet Railroad. (D) The permafrost under the Qinghai-Tibet Railroad makes it necessary to breathe bottled oxygen.

16. Select the answer with the correct number of decimal places for the following sum: 13.914 cm + 243.1 cm + 12.00460 cm = (A) 269.01860 cm (B) 269.0186 cm (C) 269.019 cm (D) 269.02 cm (E) 269.0 cm

17. The difference between a student's experimental measurement of the density of sodium chloride and the known density of this compound reflects the ___________ of the student's result. (A) accuracy (B) precision (C) random error (D) systematic error (E) indeterminate error

18. The average mass of a carbon atom is 12.011. Assuming you were able to pick up only one carbon unit, the chances that you would randomly get one with a mass of 12.011 is ___________. (A) 0% (B) 0.011% (C) about 12% (D) 12.011% (E) greater than 50%

19. A catalyst ___________. (A) changes the enthalpy of the reaction (B) does not change the activation energy (C) provides an alternate pathway to the reaction (D) does not change the effective collisions (E) is consumed when more reacting molecules are added

20. For a gas sample, which conditions of P (pressure), T (temperature), and n (molar number), respectively, are most ideal? (A) high P, high T, high n (B) low P, low T, low n (C) high P, low T, high n (D) low P, high T, high n (E) low P, high T, low n