Passage II

When fossil fuels are burned, sulfur (S) enters the air as sulfur dioxide gas (SO2), which is then converted to sulfuric acid (H2SO4) :

1) 2SO2 + O2 →2 SO3

2) SO3 + H2O → H2SO4

Rain containing the H2SO4 then deposits the sulfur into lakes.

Figure 1 shows data on the average rate of sulfur deposition in numerous lakes throughout Ontario, Canada. Figure 2 shows, for Zones 1-5 in Figure 1, the average SO42- concentration (which is a measure of deposited H2SO4), the average alkalinity (the average concentration of substances in lake water that neutralize acidity), and the average pH in lake waters versus the average rate of sulfur deposition.

Figures adapted from B. P. Neary and P. J. Dillon, "Effects of Sulfur Deposition on Lake-Water Chemistry in Ontario, Canada." ©1988 by Macmillan Journals, Ltd.

7. Based on the data in Figures 1 and 2, one would most reasonably conclude that the average pH of lake waters in Zone 6 was most likely:

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

It can be seen from Figure 1 that sulfur deposition increases sequentially from Zone 1 to Zone 6; compared with Figure 2, it can be seen from Figure 1 that pH decreases sequentially from Zone 1 to Zone 5, so it can be It is inferred that the pH of Zone 6 will be lower than that of Zone 5, so option A is reasonable.