ACT science practice test 15

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.


Sylvatic, or jungle, Yellow Fever is caused by a virus transmitted by mosquitoes from monkeys to humans. Figure 1 shows the life cycle of the mosquitoes who carry this disease. These mosquitoes' eggs do not hatch unless there is enough water for the next two stages of their life cycles. Yellow Fever is passed when an adult of these mosquitoes first bites a monkey that is infected with the virus and then bites a human.

Figure 1

A study was done on a group of ecologists who went into a jungle where the monkeys carrying the Yellow Fever virus live. These ecologists were divided into groups based on how frequently they went into the jungle. The ecologists were tested monthly for Yellow Fever. Figure 2 shows the number of new cases of Yellow Fever and the amount of rainfall in the jungle. For each group, Table 1 shows the number of ecologists in each group, number of mosquito bites, and percent of each group with Yellow Fever.

Figure 2

1. Based on Figure 1, what is essential in maintaining the mosquito population?

A. Jungle
B. Water
C. Monkeys
D. Humans

2. Based on Table 1, the average percent of ecologists affected by the yellow fever virus was closest to:

F. 20%.
G. 30%.
H. 60%.
J. 80%.

3. Suppose additional data had been gathered for Table 1 about the number of mosquito bites per month. Based on Figure 2 and Table 1, in which of the following months would you expect to have the largest total of mosquito bites per month?

A. April
B. June
C. August
D. November

4. According to Figure 2, the amount of rainfall was different for each of the following pairs of months EXCEPT:

F. May and December.
G. February and March.
H. January and October.
J. April and May.

5. Based on Table 1, as the number of trips into the jungle increased, the number of monkeys seen:

A. increased only.
B. decreased only.
C. increased, then decreased.
D. varied with no consistency.

Ethanolamines are compounds that contain both alcohol (-OH or HO-) and amine (-NH3, -RNH2, -R2NH, or -R3N) subgroups. They remove weakly acidic gases from the atmosphere of enclosed spaces such as on a submarine. An example is the use of monoethanolamine (MEA) to remove CO2 from the atmosphere as shown in Figure 1.

2 MEA(liquid) + CO2(gas) (MEA)COO-(aqueous) + (MEA)H +(aqueous) + heat

Figure 1

If the temperature rises sufficiently, ethanolamines will release any absorbed acidic gases back into the environment, creating a potential hazard.

Scientists studied the absorption properties of 2 ethanolamines (MEA and DEA).

Experiment 1

At 0°C and 1 atmosphere (atm) pressure, 1 mole (6.02 × 1023 molecules) of MEA was spread at the base of a reaction vessel containing CO2 gas at a concentration of 1,000 parts per million (ppm). As the CO2 was absorbed, its ambient concentration decreased. The scrub time (time for CO2 concentration to drop to at least 10 ppm) was measured. Longer scrub times indicate a slower rate of absorption. The experimental procedure was repeated at varying temperatures and for DEA, with results recorded in Table 1.

Experiment 2

The scrub times of MEA for different acidic gases were measured using the procedures of Experiment 1 at 26°C (see Table 2). Each of the gases listed is toxic and poses a significant safety hazard if its concentration becomes elevated within an enclosed space.

6. In which of the following ways was the procedure of Experiment 2 different from that of Experiment 1? In Experiment 2:

F. temperature was varied; in Experiment 1, the temperature was held constant.
G. temperature was held constant; in Experiment 1, the temperature was varied.
H. only MEA was used; in Experiment 1, only DEA was used.
J. only DEA was used; in Experiment 1, only MEA was used.

7. In Experiment 1, during the DEA trial at 20°C, as the time progressed from 0 to 8,190 msec, the concentration of CO2 in the vessel:

A. increased from 10 ppm to 1,000 ppm.
B. increased from 1,000 ppm to 10 ppm.
C. decreased from 10 ppm to 1,000 ppm.
D. decreased from 1,000 ppm to 10 ppm.

8. If, in Experiment 1, an additional trial were done at 12°C, the scrub times (in msec) for MEA and DEA would most likely be closest to which of the following?

F. 10,805
G. 10,985
H. 11,000
J. 11,025

9. Based on the information in the passage, which of the following is a possible chemical formula for an ethanolamine?

A. HO--(CH2)2--NH3
B. HO--(CH2CF2)2--CH3
C. H3C--(CH2)4--NH3
D. H3N--(CH2CHCl)2--NH3

10. A scientist claims that under the same conditions, DEA will always absorb CO2 at a faster rate than will MEA. Do the results of Experiment 1 support this claim?

F. No; at all temperatures tested, the scrub time for DEA was more than that for MEA.
G. No; at all temperatures tested, the scrub time for MEA was more than that for DEA.
H. Yes; at all temperatures tested, the scrub time for DEA was more than that for MEA.
J. Yes; at all temperatures tested, the scrub time for MEA was more than that for DEA.

11. Based on the results of Experiment 2, which acidic gas had the slowest absorption by MEA at 26°C?

A. HCl
B. HCN
C. H2S
D. SO2