with a radiation level of 150 rads and lesser than that of a crystal with a radiation level of
450 rads. According to Figure 1, a BGO (II) crystal with a radiation level of 150 rads has a
volume of about 35 cm^3 , and a BGO (II) crystal with a radiation level of 450 rads has a
volume of 50 cm^3 . Only (G) gives the appropriate range of values between these two
volumes.
3 . G Figure 3 gives the curve for 150 rads, so find the plot in the answer choices that matches up
most closely with the curve for 150 rads in Figure 3. Use POE. The curve starts at 0 cm^3 ,
heads in an upward direction, and maxes out around 140 cm^3 . Eliminate (F) and (J) because
these curves decrease. Eliminate (H) because this curve does not start at 0 cm^3 . Only (G)
meets all the requirements and is therefore the best answer.
4 . C Plot the information from the problem onto Figure 3. A crystal with a mass of 10 g and a
volume of 100 cm^3 matches most closely the curve appearing lowest on the figure. According
to the key, this is the curve for 450 rads, as in (C).
5 . C Use POE. Figure 1 contains a side-by-side comparison of the volumes of the crystals at
different radiation levels. The BGO (I) crystals are represented by the lighter bar, and the
BGO (II) crystals are represented by the darker bar. In all cases, the BGO (I) crystals had a
smaller volume, so eliminate (A) and (B). Figure 2 contains the masses of BGO (II) but not
BGO (I). According to the passage, though, The average mass of the BGO (I) crystals was
determined to be about 13 gm. Therefore, since the masses shown in Figure 2 are all well
above this value, it can also be inferred that BGO (I)’s mass was smaller, eliminating (D).
6 . H According to the passage, The average mass of the BGO (I) was determined to be about 13
gm. Therefore, since there are 8 whole crystals left at the end of the experiment, their total
mass can be found by multiplying the number of crystals by the mass of each: 13 gm × 8, as in
(H).
Passage IX
1 . C According to Figure 1, when the volcano releases 100 km^3 of ash, its diameter is
approximately 0.1 km, which is (C). If you had trouble with this problem, you may have been
looking at the wrong axis.
2 . F Figure 2 shows a direct relationship. As “average time elapsed” increases, “volcano
diameter” also increases. Only (F) represents this trend.
3 . A Use POE. Pick any point on the graph: For 1–5% covered, for example, the bar showing the
ash-flow of the Himalayas is lower than both the bars for the Cascades and the
