ACT Past Papers with Answers

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Suppose a researcher observed that wind speeds greater than 80 miles per hour are needed to move the rocks in the playa. This observation is consistent with which of the scientists’ explanations?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Suppose that no seismic activity was recorded in the playa where the trails left by the rocks are found. This finding would weaken which of the scientists’ explanations?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Suppose it were discovered that a particular rock formed a 200 m long trail in 72 hr. Would this discov- ery support Scientist 1’s explanation? eral hundred meters in a few hours. eral hundred meters in a few days. eral hundred meters in a few hours. eral hundred meters in a few days.

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Suppose that during one year there was no measurable movement of any rocks in the playa during the spring. Scientists 1 and 2 would most likely both agree that this was due to the absence of which of the following factors?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Suppose that air temperature in the playa varies between 4°C and 47°C. Would this information sup- port the explanation of Scientist 2 ? range. range. range. range.

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Based on Scientist 1’s explanation, a rock trail that is 33 cm wide was most likely made by a rock with approximately what width? 39 GO ON TO THE NEXT PAGE. ACT-Z04 4 4 Passage II When certain substances are added to diet cola, CO2 gas is produced, generating a foam. Two experiments were done to study this process. In each trial, an apparatus like that shown in Figure 1 was used as follows: A jar was nearly filled with H2O and fitted with a 2-holed lid. One end of a tube (Tube B) was inserted through one of the holes and submerged. The other end of Tube B was placed in an empty graduated cylinder. Another tube (Tube A) was inserted through the other hole in the lid. A certain solid substance was inserted into the other end of Tube A, and the substance was secured by a clamp. Tube A was then attached to a freshly opened bottle containing 355 mL of diet cola. The clamp was removed, releasing the substance into the diet cola. The foam that was produced traveled into the jar, and liquid was trans- ferred into the cylinder. The mass of CO2 produced was calculated based on the volume of liquid that was measured in the cylinder after foaming had ceased. Figure 1 Experiment 1 In each of Trials 1−4, a different 1 of 4 substances of equal mass—a piece of chalk, a sugar cube, a fruit-flavored piece of candy, or a mint-flavored piece of candy—was added to a bottle of diet cola at 3°C. See Table 1. Experiment 2 In each of Trials 5−8, Trial 4 from Experiment 1 was repeated, except that the temperature of the diet cola was different in each trial. See Table 2. Tables 1 and 2 adapted from Christopher J. Huber and Aaron M. Massari, “Quantifying the Soda Geyser.” ©2014 by Division of Chemical Education, Inc., American Chemical Society. Table 1 Trial Substance Volume of liquid in cylinder (mL) Mass of CO2 produced (g) 1 chalk 699 1.36 2 sugar cube 570 1.11 3 fruit candy 525 1.02 4 mint candy 631 1.23 Table 2 Trial Temperature (°C) Volume of liquid in cylinder (mL) Mass of CO2 produced (g) 5 10 598 1.130 6 25 539 0.969 7 45 501 0.844 8 60 476 0.766 bottle jar graduated cylinder Tube A Tube B substance clamp 40 GO ON TO THE NEXT PAGE. ACT-Z04 4 4

Paper 17 · ACT April 2021 · Form Z04 · Science Test

If another trial had been performed in Experiment 2 and 450 mL of liquid had been measured in the cylin- der, the temperature of the diet cola in this trial would most likely have been:

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Suppose Trial 6 had been repeated, but the bottle of diet cola had been opened and then left undisturbed at 25°C for 12 hours before it was attached to the appara- tus. Would the mass of CO2 produced in this trial likely be greater than 0.969 g or less than 0.969 g ? tion of CO2 in the diet cola would have decreased. tion of CO2 in the diet cola would have increased. of CO2 in the diet cola would have decreased. of CO2 in the diet cola would have increased.

Paper 17 · ACT April 2021 · Form Z04 · Science Test

One millimole (mmol) of CO2 has a mass of 0.044 g. How many trials resulted in the production of at least 1 mmol of CO2 ?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

According to Figure 1, which of Tube A and Tube B, if either, had at least one end submerged in a liquid before the clamp was removed?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Is the relationship between the volume of liquid in the cylinder at the end of the experiment and the mass of CO2 produced a direct relationship or an inverse relationship? in the cylinder increased, the mass of CO2 pro- duced increased. in the cylinder increased, the mass of CO2 pro- duced decreased. in the cylinder increased, the mass of CO2 pro- duced increased. in the cylinder increased, the mass of CO2 pro- duced decreased.

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Consider these steps that were performed in each trial.

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Assume that room temperature is 25°C. In how many trials was the diet cola tested at a temperature lower than room temperature? 41 GO ON TO THE NEXT PAGE. ACT-Z04 4 4 Passage III Scientists studied the effects of pH and of nickel con- centration on plant growth and on the uptake of iron and zinc by plants. Recently germinated seedlings of Species M and Species U were fed 1 of 12 nutrient solutions (Solu- tions 1−12) for 8 days and then were harvested. Solu- tions 1−12 differed only in pH and/or nickel concentration. Table 1 shows, for each species, the average dry mass of the plants that were fed each nutrient solution. Figure 1 shows, for each species, the average iron content and the average zinc content of the plants that were fed Solu- tions 1−4. Figure 1

Paper 17 · ACT April 2021 · Form Z04 · Science Test

According to Figure 1, as the nickel concentration in the nutrient solutions increased, the average iron con- tent of Species M plants: average iron or zinc content (μg/g*) 1,000 900 800 700 600 500 400 300 200 100 0 0 5 10 15 nickel concentration (μM) *μg/g = micrograms of iron or zinc per gram of plant dry mass Key Species M Species U Species M Species U iron zinc Table 1 Solution pH Nickel concentration (μM*) Average dry mass (g) of plants of Species: M U 01 7 00 33.9 10.7 02 7 05 28.8 10.7 03 7 10 23.8 09.6 04 7 15 18.7 08.5 05 6 00 33.9 09.2 06 6 05 28.8 09.2 07 6 10 23.8 08.1 08 6 15 18.7 07.0 09 5 00 27.8 07.7 10 5 05 22.7 07.7 11 5 10 17.6 06.6 12 5 15 12.4 05.4 *μM = micromoles per liter 42 GO ON TO THE NEXT PAGE. ACT-Z04 4 4

Paper 17 · ACT April 2021 · Form Z04 · Science Test

According to Table 1, the Species U plants that were fed the solution that had a pH of 6 and a nickel concen- tration of 10 μM had an average dry mass of:

Paper 17 · ACT April 2021 · Form Z04 · Science Test

According to Table 1, Species M plants that were fed a nutrient solution with which of the following combina- tions of pH and nickel concentration had the greatest average dry mass? pH nickel concentration

Paper 17 · ACT April 2021 · Form Z04 · Science Test

According to Table 1 and Figure 1, the Species M plants that were fed Solution 3 had an average zinc content of:

Paper 17 · ACT April 2021 · Form Z04 · Science Test

According to Table 1 and Figure 1, for the Species M plants that were fed Solutions 1−4, what was the order of the nutrient solutions, from the solution that resulted in the lowest average iron content to the solu- tion that resulted in the highest average iron content?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

According to Table 1, compared to the average dry mass of Species U plants that were fed Solution 3, the average dry mass of Species M plants that were fed Solution 6 was approximately: 1 _ _ 3 1 _ _ 2 43 GO ON TO THE NEXT PAGE. ACT-Z04 4 4 Passage IV Ammonia (NH3) can be produced according to the chemical equation N2 + 3H2 2NH3 The equilibrium arrow ( ) indicates that this reaction proceeds in both directions until it is at equilibrium, so that both the forward reaction (production of NH3) and the backward reaction (production of N2 and H2) occur at the same rate. Equilibrium can be shifted forward or backward by changing the temperature, pressure, or concentration of reactants or products. Two experiments were done using the following appa- ratus to produce NH3. In each trial, Steps 1−4 occurred:

Paper 17 · ACT April 2021 · Form Z04 · Science Test

According to the results of Experiment 1, for any given catalyst, as the temperature was increased, the number of cycles needed to complete the reaction:

Paper 17 · ACT April 2021 · Form Z04 · Science Test

In Experiment 1, 26 cycles were needed to complete the reaction at 450°C when which catalyst was used?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

The movement of H2 and N2 through the apparatus as Steps 1−4 occurred is best represented by which of the following expressions?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Consider the results of Experiment 1 for 375°C. All the H2 and N2 were consumed in less than 20 cycles when which catalysts were used?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

If a trial had been performed in Experiment 2 at 425°C and 225 atm, the amount of NH3 produced would most likely have been:

Paper 17 · ACT April 2021 · Form Z04 · Science Test

At 1 atm of pressure, the melting point of NH3 is −77°C and the boiling point of NH3 is −33°C. Based on this information and the description of the appara- tus, when the NH3 exited the condenser, was it more likely a solid or a liquid? was lower than the melting point of NH3 and the boiling point of NH3. was between the melting point of NH3 and the boiling point of NH3. was higher than the melting point of NH3 and the boiling point of NH3. was between the melting point of NH3 and the boiling point of NH3.

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Consider the trial in Experiment 2 that produced 550 kg of NH3. Based on Figure 1, the number of cycles that were needed to complete the reaction in this trial was most likely: 45 GO ON TO THE NEXT PAGE. ACT-Z04 4 4 Passage V As a sound wave travels through a medium, the wave becomes attenuated (loses energy). The attenuation coeffi- cient, α, is the rate at which the wave’s intensity level (a measure of sound volume) decreases with distance as a result of this energy loss; the greater the value of α, the greater the decrease in intensity level with distance. Figure 1 shows, for waves of 3 different frequencies (in hertz, Hz), how α (in decibels per kilometer, dB/km) varies with temperature in air at 10% relative humidity. Figure 1 Figure 2 shows, for waves of 3 different frequencies, how α varies with relative humidity in air at 20°C. Figure 2 Figures adapted from Richard Lord, “Calculation of Absorption of Sound by the Atmosphere.” ©2004 National Physical Laboratory. 24 21 18 15 12 9 6 3 0 α (dB/km) −20 0 20 40 60 80 100 temperature (°C) Key 1,000 Hz 500 Hz 200 Hz 14 12 10 8 6 4 2 0 α (dB/km) 10 20 30 40 50 60 70 80 90 relative humidity (percent) Key 1,000 Hz 500 Hz 200 Hz 46 GO ON TO THE NEXT PAGE. ACT-Z04 4 4

Paper 17 · ACT April 2021 · Form Z04 · Science Test

What is the approximate maximum α shown in Figure 1 for a 200 Hz sound wave in air at 10% relative humidity, and at approximately what temperature does that maximum occur? α (dB/km) temperature (°C)

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Based on Figure 2, the attenuation coefficient for a 1,000 Hz sound wave in air at 20°C reaches a minimum value at a relative humidity closest to which of the following?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

For the range of temperatures and the range of relative humidities shown in Figures 1 and 2, respectively, is α for a 200 Hz sound wave more strongly affected by changes in temperature or by changes in relative humidity? is about 0.5 dB/km in Figure 1 but about 2.5 dB/km in Figure 2. is about 2.5 dB/km in Figure 1 but about 0.5 dB/km in Figure 2. in α is about 0.5 dB/km in Figure 1 but about

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Consider a 1,000 Hz sound wave in air at 10% relative humidity. At how many of the temperatures shown in Figure 1 does α for this wave have a value of 18 dB/km ?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Suppose that 2 sound waves—a 150 Hz wave and a 1,100 Hz wave—are simultaneously emitted from a speaker into air at 20°C and 45% relative humidity. Based on Figure 2, as the waves travel away from the speaker, the intensity level of which wave will more likely decrease at the greater rate due to attenuation? for the 150 Hz wave than for the 1,100 Hz wave. for the 150 Hz wave than for the 1,100 Hz wave. lesser for the 1,100 Hz wave than for the 150 Hz wave. greater for the 1,100 Hz wave than for the 150 Hz wave.

Paper 17 · ACT April 2021 · Form Z04 · Science Test

The graph below shows, for sound waves of 3 different frequencies, how α varies with relative humidity in air at a particular temperature. Based on Figure 1, the particular air temperature is most likely which of the following? 20 16 12 8 4 0 α (dB/km) 10 20 30 40 50 relative humidity (percent) 1,000 Hz 500 Hz 200 Hz 47 GO ON TO THE NEXT PAGE. ACT-Z04 4 4 Passage VI Three studies compared the effects of 5 sweeteners (Sweeteners Q−U) on food consumption by rats and on the concentrations of leptin and ghrelin (hormones that regu- late appetite) in the blood of rats. Sweeteners Q−U differ only in the percent by mass of fructose and of glucose (see Table 1). Study 1 Each of 5 groups (Groups 1−5) of rats was assigned a solution having a 100 g/L concentration of 1 of the 5 sweeteners. Each rat was placed in a separate cage and provided unlimited access to the assigned sweetener solu- tion and to solid food for 56 days. Table 2 shows, for each group, the amounts of sweetener solution and solid food consumed per rat per day. On Day 56, blood was collected from each rat for analysis in Studies 2 and 3. Table 2 adapted from Heather R. Light et al., “The Type of Caloric Sweetener Added to Water Influences Weight Gain, Fat Mass, and Reproduction in Growing Sprague-Dawley Female Rats.” ©2009 by the Society for Experimental Biology and Medicine. Study 2 A 1 mL blood sample from each rat was placed in a separate test tube containing 0.2 mL of Indicator N (which reacts with leptin to form a blue dye). The concentration of blue dye in each tube was directly proportional to the leptin concentration in the blood sample. Table 3 shows the leptin concentration per sample for each group. Study 3 Study 2 was repeated, except that Indicator P (which reacts with ghrelin to form a yellow dye) was used instead of Indicator N. The concentration of yellow dye in each tube was directly proportional to the ghrelin concentration in the blood sample (see Table 4). Tables 3 and 4 adapted from Andreas Lindqvist, Annemie Baelemans, and Charlotte Erlanson-Albertsson, “Effects of Sucrose, Glucose and Fructose on Peripheral and Central Appetite Signals.” ©2008 by Elsevier B.V. Table 3 Group Sweetener Leptin concentration per sample (pM*) 1 Q 804 2 R 622 3 S 553 4 T 475 5 U 251 *picomolar Table 4 Group Sweetener Ghrelin concentration per sample (pM) 1 Q 0,852 2 R 1,125 3 S 1,279 4 T 1,450 5 U 1,758 Table 1 Sweetener Percent by mass of: fructose glucose Q 000 100 R 042 058 S 050 050 T 055 045 U 100 000 Table 2 Group Sweetener Amount consumed per rat per day sweetener solution (mL) solid food (g) 1 Q 73 09 2 R 55 14 3 S 52 16 4 T 48 18 5 U 29 23 48 GO ON TO THE NEXT PAGE. ACT-Z04 4 4 49 ACT-Z04 4 4 34. In Study 1, as the ratio of fructose to glucose in the sweetener solutions increased, the amount of sweet- ener solution consumed per rat per day:

Paper 17 · ACT April 2021 · Form Z04 · Science Test

J ___

Paper 17 · ACT April 2021 · Form Z04 · Science Test

In Study 1, the amount of sweetener solution con- sumed daily by each rat could be measured because which of the following steps had been taken? restricted.

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Suppose that a sweetener composed of 46% fructose and 54% glucose by mass had been tested in Study 1. Based on Table 1 and the results of Study 3, the ghrelin concentration per sample would most likely have been:

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Consider the claim “The group of rats that consumed the lowest amount of solid food per rat per day was also the group that had the lowest concentration of leptin per sample.” Do the results of Studies 1 and 2 support this claim? amount of solid food per rat per day and also had the lowest concentration of leptin per sample. amount of solid food per rat per day and also had the lowest concentration of leptin per sample. amount of solid food per rat per day, but the rats in Group 5 had the lowest concentration of leptin per sample. amount of solid food per rat per day, but the rats in Group 1 had the lowest concentration of leptin per sample.

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Which of the following groups of rats should have been included in Study 1 to serve as a control for the effect of consuming a sweetener solution on the con- sumption of solid food by rats? A group of rats that had access:

Paper 17 · ACT April 2021 · Form Z04 · Science Test

Consider the sweetener that resulted in a solid food consumption of 16 g per rat per day in Study 1. Based on Table 1, how many grams of fructose would be present in 200 g of this sweetener?

Paper 17 · ACT April 2021 · Form Z04 · Science Test

The experimental designs of Studies 2 and 3 were identical with respect to which of the factors listed below, if either? I. The chemical indicator that was used II. The hormone with which the chemical indica- tor reacted END OF TEST 4 STOP! DO NOT RETURN TO ANY OTHER TEST. 50 Scoring Keys for Form Z04 Use the scoring key for each test to score your answer document for the multiple-choice tests. Mark a “1” in the blank for each question you answered correctly. Add up the numbers in each reporting category and enter the total number correct for each reporting category in the blanks provided. Also enter the total number correct for each test in the blanks provided. The total number correct for each test is the sum of the number correct in each reporting category. Test 1: English—Scoring Key Number Correct (Raw Score) for: Production of Writing (POW) _______ (23) Knowledge of Language (KLA) _______ (12) Conventions of Standard English (CSE) _______ (40) Total Number Correct for English Test _______ (POW + KLA + CSE) (75) Key Reporting Category* POW KLA CSE