Question 10 Answer and Explanation _ACT December 2010 Form 62E Science Section

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 SO₄^2-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.

10. Given the information provided, lake waters in which of the following zones had the greatest capacity to neutralize acidity?

F. Zone 1

G. Zone 2

H. Zone 3

J. Zone 4

Answer and Explanation

Your Answer is

Correct Answer is F

Explanation

According to the definition of average alkalinity given in the article, it can be found that the larger the value, the stronger the ability to neutralize acid. Therefore, according to the figure in the middle of Figure 2, it can be seen that the alkalinity of Zone 1 is the largest, so the ability to neutralize acid is the strongest.