ACT Past Papers with Answers

Paper 20 · ACT June 2020 · Form C02 · Science Test

In Experiment 1, how many trials, in total, resulted in an average angle of detachment of 130° or less? 9

Paper 20 · ACT June 2020 · Form C02 · Science Test

According to the results of Experiment 1, which of the following combinations of flow rate and platform tex- ture resulted in an average angle of detachment of 150°? flow rate platform (L/min) texture smooth smooth fine rough fine rough

Paper 20 · ACT June 2020 · Form C02 · Science Test

0 L/min, what is the order of platform texture, from the texture that resulted in the smallest average angle of detachment to the texture that resulted in the largest average angle of detachment? ACT-COE 39 GO ON TO THE NEXT PAGE. 4 Passage I| 0000 In aqueous solutions, vitamin C (C,Hg0,) reacts with iodine (1z) according to the balanced chemical equation CH 06+12 → C,H,O, + 2HI The amount of vitamin C in a solution can be determined by performing a titration. The titrant (a solution containing a known concentration of 12) is slowly added to the analyte (a solution containing a particular concentration of vitamin C), and a chemical reaction occurs. This process is monitored by adding an indicator to the analyte. The indi- cator is a colorless starch solution that changes to a dark color by reacting with I, when no more vitamin C remains, signaling the end of the titration. Students performed titrations to determine the amount of vitamin C in 4 different types of pulp-free juice. Experiment 1 A 0.20 mg/mL vitamin C solution was prepared. A

Paper 20 · ACT June 2020 · Form C02 · Science Test

lost hydrogen atoms.

Paper 20 · ACT June 2020 · Form C02 · Science Test

If a platform rotation angle of 150° had been tested in Experiment 2, the average contact area would most likely have been: and 220 mm greater than 265 mm?.

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on the results of Experiment 1, for a flow rate of

Paper 20 · ACT June 2020 · Form C02 · Science Test

Consider the steps performed in Experiment 2 that are listed below.

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on the results of Experiments 1 and 2, which of the juices that were tested contained the greatest con- centration of vitamin C?

Paper 20 · ACT June 2020 · Form C02 · Science Test

Suppose that the titration of a particular vitamin C solution requires 31 drops of the I solution used in Experiment 1 to cause the indicator to change color. Based on the results of Experiment 1, the vitamin C solution has an approximate concentration of:

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on the results of Experiments 1 and 2, the con- centration of vitamin C in the lemon juice was closest to which of the following? 4

Paper 20 · ACT June 2020 · Form C02 · Science Test

Suppose that a sample of apple juice had been titrated in Experiment 2 and the concentration of vitamin C in the apple juice was determined to be 0.10 mg/mL. Based on the results of Experiment 1, What Is the mini- mum number of drops of the I, solution that would have been required to change the indicator in the apple juice solution to a dark color? 4 38

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on the chemical equation in the passage, when vitamin C reacted with I, in the experiments, vita- min C:

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on the results of Experiment 1, what approxi- mate mass of vitamin C in a 1.0 mL sample reacted with each drop of the I, solution? ACT- •C02 41 GO ON TO THE NEXT PAGE. 4 Passage III All known exoplanets (planets in orbit about stars other than the Sun) are too distant from Earth to be studied in detail, so mathematical models have been developed to help predict their properties. Figures 1-3 each show how a different property varies with altitude above the surface of Earth and above the surfaces of 2 hypothetical exoplanets: Planet X and Planet Y. Figure 1 shows how atmospheric temperature, T (in kelvins, K), varies; Figure 2 shows how atmospheric pressure, P (in atmospheres, atm), varies; and Figure 3 shows how gravitational field strength, g (in new- tons per kilogram, N/kg), varies. 400 Planet X 350 300- Earth| 250 200- 150- 100- 50- 0- 0 Planet Y 25 50 75 altitude (km) 100 125 150 Figure 1

Paper 20 · ACT June 2020 · Form C02 · Science Test

According to Figure 1, at approximately what altitude above their respective surfaces do Planets X and That temperatur atmospheric temperature, and what is temperature (K) 225 275 140 140 225 275 ACT-C02 42 GO ON TO THE NEXT PAGE. 4

Paper 20 · ACT June 2020 · Form C02 · Science Test

According to Figure 2, which of the following graphs best represents the altitude above the surface of Earth, of Planet X, and of Planet Y at which P = 0.3 atm ? 50 50 40 30 20 10 altitude (km) 40- 30 20 10 0 0 Planet X Planet Y 50 altitude 20 10 0 Planet X* Planet Y 50 altitude (km) 40 30 20 10 0 4

Paper 20 · ACT June 2020 · Form C02 · Science Test

Atmospheric density and P are directly proportional to each other. Based on Figure 2, which planet more likely has the more dense atmosphere at an altitude of 5 km, Earth or Planet Y ? than P for Planet Y. than P for Planet Y. less than P for Earth. greater than P for Barth.

Paper 20 · ACT June 2020 · Form C02 · Science Test

At the surface of a planet, g is given by the equation GM 8= where G is a constant, M is the planet's mass, and R is the planet's radius. Assume that Earth, Planet X, and Planet Y have equal radii. Based on Figure 3, which planet has the greatest mass?

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on Figure 1, is the average kinetic energy of the gas particles in Earth's atmosphere more likely greater at an altitude of 40 km or 80 km ? gas particles is directly proportional to gas temperature. gas particles is inversely proportional to gas temperature. gas particles is directly proportional to gas temperature. gas particles is inversely proportional to gas temperature. Planet X 4 Planet Planet Planet

Paper 20 · ACT June 2020 · Form C02 · Science Test

The gravitational field strength at the surface of Planet X is approximately what percent of the gravita- tional field strength at the surface of Earth? 60% 80% ACT-C02 43 GO ON TO THE NEXT PAGE. 4 Passage IV As sound waves travel through seawater, some of their energy is absorbed by the seawater. This sound absorption depends on several factors, including the pH of the water, the depth below the water's surface at which the sound waves travel, the frequency of the sound waves, the water temperature, and the water's salinity (concentration of dis- solved salts in the water). Figures 1, 2, and 3 show-under the given conditions, respectively-how sound absorption (in decibels per kilometer, dB/km) varies with frequency (in kilohertz, kHz), temperature (in °C), and salinity (in parts per thousand, ppt; 1 ppt = 1 g/kg). Conditions pH = 8.0 depth = 0.05 km temperature = 20°C salinity = 35 ppt / 4 Conditions pH = 8.0 depth = 0.05 km frequency = 10 kHz temperature = 20°C 0 5 10 15 20 salinity (ppt) Figure 3 Water." @1998 by Acoustical Society of America. 25 30 35 sound absorption (dB/km) 0 2 4 6 8 10 12 14 16 18 20 frequency (kHz) Figure 1 sound absorption (dB/km)

Paper 20 · ACT June 2020 · Form C02 · Science Test

According to Figure 2, at which of the following water temperatures is the sound absorption by the seawater closest to 0.67 dB/km ?

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on Figure 1, the sound absorption at a frequency sound absorpion at a requency om2 as great as the

Paper 20 · ACT June 2020 · Form C02 · Science Test

Source question 23. Refer to the source image.

Paper 20 · ACT June 2020 · Form C02 · Science Test

Suppose sound absorption by seawater is measured under the conditions given in Figure 2, except that the frequency of the sound waves is 16 kHz. Based on Fig- ures 1 and 2, If the temperature of the seawater is 3°C will the sound absorption more likely be less than

Paper 20 · ACT June 2020 · Form C02 · Science Test

Source question 25. Refer to the source image.

Paper 20 · ACT June 2020 · Form C02 · Science Test

Consider in Figure 1 how sound absorption changes as the frequency of the sound waves increases. As the wavelength (NOT frequency) of the sound waves increases, does sound absorption increase or decrease? increases. decreases. increases. decreases. ACT-C02 45 GO ON TO THE NEXT PAGE. 4 Passage V 0000 Giant puffball mushrooms (GPMs) have belowground and aboveground structures. Belowground, tubelike threads called hyphae extend throughout the soil. Aboveground, the visible portion of the GPM is referred to as a basidio- carp. When some GPMs are disrupted, such as when they are stepped on by an animal, a cloud of particles resem- bling smoke is released from the basidiocarp. Two students discuss the function of the hyphae and basidiocarps in GPMs and also discuss the contents of the cloud of parti- cles released when the basidiocarp is disrupted Student 1 The basidiocarps of GPMs are reproductive structures. When cells in the basidiocarp are mature, they produce, by meiosis, cells called spores. The spores are stored directly below the surface of the basidiocarp until the basidiocarp is disrupted. After release, a spore may settle in the soil, ger- minate, and then form a new hypha. When a newly formed hypha meets another newly formed hypha, they fuse and then produce a new basidiocarp. Young basidiocarps do not yet contain spores and thus do not produce a cloud of parti- cles when disrupted. The hyphae of a GPM acquire nutrients for the organ- ism from organic matter in the soil. The nutrients are then transported to feed the aboveground structure. Student 2 The hyphae of GPMs are reproductive structures, sim- ilar to the roots of some plants that reproduce asexually. To produce a new GPM, the hyphae grow away from the parental GPM to another location in the soil. Once the hyphae have grown away from the parental GPM, the hyphae produce a new basidiocarp. After the new basidio- carp has formed, the newly grown hyphae separate from the parental hyphae. Like the leaves of plants, the basidiocarps of GPMs produce energy for the organisms through the process of photosynthesis. Basidiocarps also function as deterrents to ) 4

Paper 20 · ACT June 2020 · Form C02 · Science Test

According to Student 1 and Student 2, respectively, what is the main functional component contained in the cloud of particles from a disrupted basidiocarp? Student 1 Student 2 spores carbohydrates toxins toxins carbohydrates toxins spores

Paper 20 · ACT June 2020 · Form C02 · Science Test

Student 1 implies that the basidiocarps of some GPMs do not release a cloud of particles when disrupted because the: ductively mature. GPM. for the GPM.

Paper 20 · ACT June 2020 · Form C02 · Science Test

Student 2 indicates that the hyphae of a GPM are pri- marily involved in producing: ACT-C02 46 GO ON TO THE NEXT PAGE. 4

Paper 20 · ACT June 2020 · Form C02 · Science Test

Consider the diagram of the life cycle of a GPM shown below. basidiocarp hyphae This diagram is consistent with the discussion(s) of which students), if either?

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on Student 1's discussion, spore germination can best be described as a process that directly results in the production of new: toxins.

Paper 20 · ACT June 2020 · Form C02 · Science Test

Do Student 1 and Student 2, respectively, describe the portion of the GPM involved in obtaining energy as being located aboveground or belowground? Student 1 Student 2 aboveground belowground aboveground belowground

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on Student 2's discussion, why do newly formed hyphae separate from parental hyphae after, rather than before, the formation of a new basidiocarp? other organisms. GPM. organisms. GPM. ACT-C02 47 GO ON TO THE NEXT PAGE. 4 Passage VI A semiconductor is a substance whose electrical prop- erties can be fine-tuned by doping (replacing some of the substance's atoms with atoms of another substance). Silicon is one example of a semiconductor. A scientist per- formed 2 experiments to study the electrical resistance, R, of silicon wafers (thin blocks) that had been doped. 4 105- 10*9 10°- 102 10 1 101- boron. arsenic-y Experiment / The scientist placed 15 silicon wafers into a tempera- ture-controlled chamber. The length and width of each wafer was 10.95 mm, and the thickness of each wafer was

Paper 20 · ACT June 2020 · Form C02 · Science Test

Suppose that in Experiment 2 the scientist had mea- sured a resistance of 22 S2 for the boron-doped wafer. The temperature of the wafer at the time of this mea- surement would most likely have been;

Paper 20 · ACT June 2020 · Form C02 · Science Test

What factor was constant in Experiment 1 but was NOT constant in Experiment 2?

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on the results of Experiments 1 and 2, which of the following statements best summarizes the relation- ship between R and No and the relationship between R and T? R increased as:

Paper 20 · ACT June 2020 · Form C02 · Science Test

Did the scientist investigate whether the resistance of a doped wafer is affected by the wafer's dimensions? dimensions. dimensions. dimensions. 4

Paper 20 · ACT June 2020 · Form C02 · Science Test

In Experiments 1 and 2, the scientist most likely waited between setting T and measuring R to ensure that the: chamber. the chamber. greater laboratory environment. doping atoms within each wafer were not in ther- mal equilibrium with the chamber.

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on the results of Experiment 1, the ohmmeter shown in Figure 1 is most likely connected to the wafer doped with which type of atoms and at what doping concentration? type of doping atoms boron boron arsenic arsenic Na (atoms/cm') 10'5 10'6 10'5 1016

Paper 20 · ACT June 2020 · Form C02 · Science Test

Based on the value of R for the pure silicon wafer and the data in Figure 2, does replacing some of the silicon atoms in a silicon wafer with doping atoms make the wafer a better conductor or a better insulator? doped wafer was less than that of the pure silicon doped wafer was greater than that of the pure sili- doped wafer was less than that of the pure silicon doped wafer was greater than that of the pure sili- END OF TEST 4 STOP! DO NOT RETURN TO ANY OTHER TEST. ACT-C02 49 • Scoring Keys for Form C02 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 Test 1: English-Scoring Key Reporting Category* POW KLA CSE 1. 2. Key A G Reporting Category* Key POW KLA CSE 39. C 40