ACT science practice test 70

Directions: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.

You are NOT permitted to use a calculator on this test.

Solubility refers to the ability of one substance, the solute, to dissolve in another (the solvent). The balance of molecules between the solvent and the solute determines the solubility of one substance in another. Factors such as temperature and pressure will alter this balance, thus changing the solubility.

Experiments to determine the solubility of methane and carbon dioxide in polyamide (PA-11) were performed in the temperature range 50–90°C, and the pressure range 50–150 atm for methane and 20–40 atm for carbon dioxide. Table 1 displays the solubility (sol) of methane in PA-11. Table 2 shows the solubility (sol) of carbon dioxide in PA-11.

Solubility = (g gas/g PA-11) × 103

Table 1—Methane


Table 2—Carbon Dioxide


Figure 1 shows the pressurization cycle for methane at 100 atm and 50°C. The mass gain divided by the net polyamide mass determines the solubility of the gas.


Figure 1

1. Which of the following substances did NOT become more soluble as pressure increased?

F. Methane at 70°C
G. Methane at 50°C
H. Carbon dioxide at 50°C
J. Carbon dioxide at 90°C

2. According to Table 2, at which temperature was carbon dioxide the most soluble under pressure of 31.1 atm?

A. 50°C
B. 70°C
C. 90°C
D. 100°C

3. Figure 1 supports which of the following claims about polyamide mass gain over time?

F. The polyamide steadily gained mass.
G. The polyamide lost mass over time.
H. The polyamide gained mass at first, and then lost mass.
J. The polyamide quickly gained mass and then leveled off.

4. If the experiment was repeated at a temperature of 90°C and a pressure of 80 atm, the solubility of methane would be closest to:

A. 2.61 atm.
B. 3.75 atm.
C. 5.08 atm.
D. 14.0 atm.

5. Based on the results shown in Table 2, which of the following conclusions can be drawn regarding the relationship between pressure and solubility?

F. Solubility increases with pressure only above 70°C.
G. As pressure increases, solubility decreases.
H. As pressure increases, so does solubility.
J. There is no correlation between pressure and solubility.

6. In this experiment, which substance functioned as the solvent?

A. Methane
B. Carbon dioxide
C. Mass
D. Polyamide

As shown in Figures 1 and 2, the composition of soil varies by zone. Scientists wanted to determine which types of prairie plants grew best in which zones. To accomplish this, they visited prairies in Zone 3 and in Zone 4 and determined average plant height and root depth (see Table 1). They also looked at several 1-acre plots in both Zone 3 and Zone 4, and recorded the average number of each type of plant found (see Figure 3).


Figure 1


Figure 2


Table 1



Figure 3

7. In which zone is clay found at a depth of –3.5m?

F. Zone 3
G. Zone 4
H. Zones 3 and 4
J. Neither Zone 3 nor 4

8. Of the prairie plants studied, which had the tallest average plant height?

A. Aster
B. Kentucky Blue Grass
C. Indian Grass
D. Compass Plant

9. Based on the data in Figure 3, which of the following can be concluded about the prevalence of plants per zone?

F. The prairie plants studied grow more easily in Zone 4.
G. The prairie plants studied grow more easily in Zone 3.
H. The prairie plants studied grow equally well in Zone 3 and Zone 4.
J. No conclusion can be drawn about the prevalence of plant growth per zone.

10. A plant growing in which zone would have roots that reach clay first?

A. Zone 3
B. Zone 4
C. None of the plants studied have roots that would reach clay.
D. Plants in Zone 3 and Zone 4 would reach clay at the same depth.

11. The average Lead Plant growing in Zone 3 would have roots that, at their deepest point, reach down to which of the following soil layers?

F. Sandy clay
G. Clay
H. Gravel
J. Bedrock