ACT Past Papers with Answers

Paper 61 · ACT June 2009 · Form 67C · Science Test

During which of the following years were small seeds likely most abundant on Island B ?

Paper 61 · ACT June 2009 · Form 67C · Science Test

Study 1 differed from Study 2 in which of the follow- ing ways? not during Study 2. but not during Study 2. during Study 1 but not during Study 2. during Study 2 but not during Study 1.

Paper 61 · ACT June 2009 · Form 67C · Science Test

It is most likely that the researchers tagged the birds that they captured during Study 1 to: on Island A. sured multiple times during Study 1. sured only once during Study 1.

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on the results of Study 2, would a finch with a beak depth of 9.4 mm or a finch with a beak depth of

Paper 61 · ACT June 2009 · Form 67C · Science Test

A researcher hypothesized that there would be more variation in the beak depths measured for the G. fortis finches when they were forced to compete with another finch species for seeds. Do the results of Study 1 support this hypothesis? Island B. Island A. Island B. Island A. average beak depth (mm) 1 9 7 6 1 9 7 7 1 9 7 8 1 9 7 9 1 9 8 0 1 9 8 1 1 9 8 2 1 9 8 3 1 9 8 4 1 9 8 5 year dry dry dry wet GO ON TO THE NEXT PAGE. ACT-67C-PRACTICE 4 4 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 43 Passage II Substances in the atmosphere, such as Cu2+ , Zn2+ , Cl− , and SO4 2− ions, are carried down to Earth’s surface by precipitation. This process is known as wet deposition. Cu2+ and Zn2+ ions are put into the atmosphere by high- temperature combustion processes. The presence of Cl− and SO4 2− ions in the atmosphere can be attributed to road- salt dust and electrical power generation, respectively. Study 1 A rain gauge, placed on the roof of a 1-story building, at a specific urban site was used to collect precipitation over a 12-month period. At the same time each evening, the amount of precipitation in the rain gauge was recorded, after which the collected precipitation was emptied from the gauge and stored. (Assume no measurable evaporation occurred during any day.) Figure 1 shows the measured monthly precipitation in centimeters. Figure 1 At the end of each month, all the samples collected during that month were mixed, and some of this combined sample was analyzed for the concentrations of Cu2+ and Zn2+ ions. Using these data, the monthly wet deposition of each substance, in micrograms (μg) per meter2 , was calcu- lated (see Figure 2). Figure 2 Study 2 Another portion of the combined sample for each month was analyzed for the concentrations of Cl− and SO4 2− ions. Using these data, the monthly wet deposition of each substance, in milliequivalents (meq) per m2 , was calculated (see Figure 3). Figure 3 Study 3 The annual wet deposition of Cu2+ and of Zn2+ for the 12-month period, in μg/m2 , was calculated for the urban site (the source of the Cu2+ and Zn2+ ) and also for Rural Sites 1 and 2, located 50 km and 100 km east, respectively, of the urban site (see Figure 4). Figure 4 Figures adapted from Kathryn Conko et al., “Atmospheric Wet Deposition of Trace Elements to a Suburban Environment, Reston, Virginia, USA.” ©2004 by Elsevier, Ltd. Zn2+ Cu2+ 4,000 3,000 2,000 1,000 800 600 400 200 0 annual wet deposition (μg/m 2 ) urban site Rural Site 1 Rural Site 2 Key ion J F M A M J J A S O N D month 10 8 6 4 2 0 10 8 6 4 2 0 0 0 monthly wet deposition (meq/m 2 ) monthly wet deposition (meq/m 2 ) Cl− SO4 2− month J 800 600 400 200 0 F M A M J J A S O N D 800 600 400 200 0 150 100 50 0 150 100 50 0 monthly wet deposition (μg/m 2 ) monthly wet deposition (μg/m 2 ) Cu2+ Zn2+ J 20 15 10 5 0 F M A M J J A S O N D month monthly precipitation (cm) 20 15 10 5 0 GO ON TO THE NEXT PAGE. ACT-67C-PRACTICE 4 4 44 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 44 45

Paper 61 · ACT June 2009 · Form 67C · Science Test

According to Figure 1, over the 12-month period, the monthly precipitation at the urban site was maximum in February and minimum in July. According to Figures 2 and 3, the wet deposition of which ion was also maximum in February and minimum in July? 2−

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on the results of Study 1, the average monthly wet deposition for Cu2+ over the 12-month period was: . and 75 μg/m2 . and 100 μg/m2 . .

Paper 61 · ACT June 2009 · Form 67C · Science Test

9 mm more likely have had a greater chance of sur- vival during 1977 ? average, the size of available seeds is larger during dry years. average, the size of available seeds is smaller during dry years. average, the size of available seeds is larger during dry years. average, the size of available seeds is smaller during dry years.

Paper 61 · ACT June 2009 · Form 67C · Science Test

Suppose there had been no precipitation during 1 entire month of the 12-month period. Based on the information provided, during that month there would have been: and Zn2+ , but no wet deposition of Cl− and SO4 2− . and Zn2+ , but significant wet deposition of Cl− and SO4 2− .

Paper 61 · ACT June 2009 · Form 67C · Science Test

According to Study 3, as distance from the urban site increased, the annual wet deposition: and Zn2+ . but decreased for Zn2+ . and Zn2+ . and Zn2+ .

Paper 61 · ACT June 2009 · Form 67C · Science Test

Which of the following variables was kept constant in Study 2 ? GO ON TO THE NEXT PAGE. ACT-67C-PRACTICE 4 4 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 45 Passage III Cloud cover is the percent of Earth’s surface covered by clouds. Cloud cover may increase because of an increase in the cosmic ray flux (number of high-energy par- ticles from space reaching Earth per m2 per hour). Table 1 shows how Earth’s cover of low clouds (0 km to 3.2 km altitude) varies with the cosmic ray flux. Figures 1−3 show the relative cosmic ray flux, RCRF (the percent below the flux measured on October 1, 1965), and the monthly aver- age cover of high clouds (6.0 km to 16.0 km altitude), middle clouds (3.2 km to 6.0 km altitude), and low clouds, respectively, from January 1980 to January 1995. Table 1 adapted from E. Palle Bagó and C. J. Butler, “The Influence of Cosmic Rays on Terrestrial Clouds and Global Warming.” ©2000 by Institute of Physics Publications, Ltd. Figure 1 Figure 2 Figure 3 Figures adapted from Nigel Marsh and Henrik Svensmark, “Low Cloud Properties Influenced by Cosmic Rays.” ©2000 by The American Physical Society. Jan. 1980 Jan. 1985 Jan. 1990 Jan. 1995 RCRF (%) year monthly average cover of low clouds (%) monthly average cover of clouds RCRF Key 0 2 4 6 8 Jan. 1980 Jan. 1985 Jan. 1990 Jan. 1995 RCRF (%) year monthly average cover of middle clouds (%) monthly average cover of clouds RCRF Key 0 2 4 6 8 Jan. 1980 Jan. 1985 Jan. 1990 Jan. 1995 RCRF (%) monthly average cover of high clouds (%) year monthly average cover of clouds RCRF Key 0 2 4 6 8 Table 1 Cosmic ray flux (particles/m2 /hr) Cover of low clouds (%) 340,000 27.8 360,000 28.1 380,000 28.4 400,000 28.7 420,000 29.0 GO ON TO THE NEXT PAGE. ACT-67C-PRACTICE 4 4 46 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 46 47

Paper 61 · ACT June 2009 · Form 67C · Science Test

The percent of Earth’s surface covered by high clouds in January 1987 was closest to which of the following?

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on Table 1, a cosmic ray flux of 440,000 parti- cles/m2 /hr would correspond to a cover of low clouds that is closest to which of the following?

Paper 61 · ACT June 2009 · Form 67C · Science Test

Is the statement “The monthly average cover of low clouds is more directly correlated with cosmic ray flux than is the monthly average cover of high clouds” con- sistent with Figures 1 and 3 ? cover of low clouds more closely parallels the plot for RCRF. cover of high clouds more closely parallels the plot for RCRF. of low clouds more closely parallels the plot for RCRF. of high clouds more closely parallels the plot for RCRF.

Paper 61 · ACT June 2009 · Form 67C · Science Test

0 km is above 0°C. air temperature at altitudes from 3.2 km to 6.0 km is at or below 0°C. air temperature at altitudes from 6.0 km to 16.0 km is at or below 0°C. m i d d l e c l o u d s cloud cover h i g h c l o u d s l o w c l o u d s m i d d l e c l o u d s cloud cover h i g h c l o u d s l o w c l o u d s m i d d l e c l o u d s cloud cover h i g h c l o u d s l o w c l o u d s m i d d l e c l o u d s cloud cover h i g h c l o u d s l o w c l o u d s GO ON TO THE NEXT PAGE. ACT-67C-PRACTICE 4 4 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 47 Passage IV Acid-base titration is a technique in which precise volumes of a titrant (an acid or base solution) are added incrementally to a known volume of a sample solution (a base or acid solution, respectively). This process can be monitored by adding an acid-base indicator (a substance that changes color over a certain pH range) to the sample solution or by measuring the sample solution’s conductiv- ity. Conductivity (measured in kilosiemens per centimeter, kS/cm) is a measure of a substance’s ability to conduct electricity. Two titration experiments were done at 25°C using a

Paper 61 · ACT June 2009 · Form 67C · Science Test

High clouds are composed primarily of ice crystals, whereas low clouds are composed primarily of water droplets. This difference is most likely because the average air temperature at altitudes from: average air temperature at altitudes from 3.2 km to

Paper 61 · ACT June 2009 · Form 67C · Science Test

In Experiment 1, the sample solution was yellow at which of the following values for the volume of titrant added?

Paper 61 · ACT June 2009 · Form 67C · Science Test

In Experiment 2, the sample solution was neutral at which of the following values for the volume of titrant added? volume of titrant added (mL)

Paper 61 · ACT June 2009 · Form 67C · Science Test

In Experiment 1, if 2.30 mL of titrant had been added to the sample solution, the conductivity would most likely have been:

Paper 61 · ACT June 2009 · Form 67C · Science Test

In Experiment 2, which solution was the titrant and which solution was the sample solution? titrant sample solution

Paper 61 · ACT June 2009 · Form 67C · Science Test

In Experiments 1 and 2, the probe that was placed in the sample solution most likely did which of the following? the solution the solution

Paper 61 · ACT June 2009 · Form 67C · Science Test

A chemist claimed that in Experiment 2, the pH of the sample solution was greater at a value of 0.2 mL of titrant added than at a value of 1.8 mL of titrant added. Do the results of Experiment 2 support this claim? sample solution was yellow, and at a value of

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on Student 2’s discussion, Algol B is part of the present Algol system because of which of the follow- ing forces exerted on Algol B by the original Algol system?

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on Student 1’s discussion and Fact 4, while matter flowed between Algol A and Algol B, Algol B produced the majority of its energy by fusing: center. surrounding its center. center. surrounding its center.

Paper 61 · ACT June 2009 · Form 67C · Science Test

Suppose that chemical composition is uniform among stars formed from the same cloud of gas and dust, but that chemical composition varies among stars formed from different clouds of gas and dust. Student 2 would most likely agree with which of the following state- ments comparing the chemical compositions of the stars in the present-day Algol system at the time they formed? compositions. compositions. compositions. composition.

Paper 61 · ACT June 2009 · Form 67C · Science Test

If the mass of the Sun is 2.0 × 1030 kg, what is the mass of Algol C ? kg kg kg kg

Paper 61 · ACT June 2009 · Form 67C · Science Test

Which of the following statements best explains why the reaction described in Fact 3 requires a high temper- ature and pressure? charges attract each other. charges repel each other. charges attract each other. charges repel each other. GO ON TO THE NEXT PAGE. ACT-67C-PRACTICE 4 4 50 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 50 51

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on Fact 5 and Student 1’s discussion, which of the 3 stars in the Algol system, if any, was most likely the first to become an MS star?

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on Fact 5, would Student 2 agree that by the time Algol A stops being an MS star, Algol A will have spent as much time being an MS star as Algol B spent being an MS star? always been more massive than Algol B. always been less massive than Algol B. always been more massive than Algol B. always been less massive than Algol B. GO ON TO THE NEXT PAGE. ACT-67C-PRACTICE 4 4 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 51 Passage VI Three experiments were done using CO2, krypton (Kr), or O2. For each gas:

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on Figure 2, if 13 g of Kr had been added to the 6 L vessel, the pressure would have been:

Paper 61 · ACT June 2009 · Form 67C · Science Test

Suppose the experiments had been repeated, except with a 5 L vessel. Based on Figures 1 and 2, the pres- sure exerted by 7 g of CO2 would most likely have been:

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on Figures 1 and 2, for a given mass of O2 at 22°C, how does the pressure exerted by the O2 in a 6 L vessel compare to the pressure exerted by the O2 in a 3 L vessel? In the 6 L vessel, the O2 pressure will be:

Paper 61 · ACT June 2009 · Form 67C · Science Test

Which of the following best explains why equal masses of O2 and CO2 at the same temperature and in the same-size vessel had different pressures? The pres- sure exerted by the O2 was: gram than there were CO2 molecules per gram. gram than there were CO2 molecules per gram. per gram than there were CO2 molecules per gram. gram than there were CO2 molecules per gram.

Paper 61 · ACT June 2009 · Form 67C · Science Test

Suppose the experiment involving O2 and the 6 L vessel had been repeated, except at a room temperature of 14°C. For a given mass of O2, compared to the pres- sure measured in the original experiment, the pressure measured at 14°C would have been: temperature. temperature. to temperature. to temperature. 1 _ _ 2 pressure (torr) CO2 10 1,000 800 600 400 200 0 8 6 4 2 0 mass of gas added (g) 6 L vessel O2 Kr pressure (torr) CO2 10 2,000 1,600 1,200 800 400 0 8 6 4 2 0 mass of gas added (g) 3 L vessel O2 Kr GO ON TO THE NEXT PAGE. ACT-67C-PRACTICE 4 4 52 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 52 53 Passage VII The human threshold of hearing is the minimum intensity at each sound frequency required for a sound to be heard by humans. The human threshold of pain is the maximum intensity at each sound frequency that humans can tolerate without pain. The figure below displays, for sounds in water and in air, the human thresholds of hearing and of pain. The figure also shows S, the percent increase in air density and water density that accompanies the compression of air and water by sound waves of given intensities. Sound intensities are given in decibels (db) and frequencies are given in hertz [(Hz); 1 Hz = 1 cycle/sec]. Figure adapted from Rita G. Lerner and George L. Trigg, eds., Encyclopedia of Physics, 2nd ed. ©1991 by VCH Publishers, Inc.

Paper 61 · ACT June 2009 · Form 67C · Science Test

According to the figure, which of the following is clos- est to the lowest frequency that can be heard by a human being?

Paper 61 · ACT June 2009 · Form 67C · Science Test

As humans age, it is common for selective hearing loss to occur at high sound frequencies. Which of the fol- lowing figures best illustrates this loss?

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on the figure, a sound of a given frequency will have the highest intensity for which of the following sets of conditions? Sound is passing through: 000S000 % %

Paper 61 · ACT June 2009 · Form 67C · Science Test

A student hypothesized that sounds of any intensity at a frequency of 105 Hz would be painful for humans to hear. Do the data in the figure support this hypothesis? constant with changes in frequency. Hz, the threshold of pain increases. Hz. stant with changes in frequency.

Paper 61 · ACT June 2009 · Form 67C · Science Test

Based on the figure, does S depend on the frequency of a sound wave of a given intensity? constant. constant. Key before loss after loss threshold of hearing intensity frequency threshold of hearing intensity frequency threshold of hearing intensity frequency threshold of hearing intensity frequency intensity (db) frequency (Hz) 0 20 40 60 80 100 120 140 160 180 200 220 240 1 × 10 1 1 × 10 2 10 3 10 4 10 5 2 4 6 8 2 × 10 1 4 × 10 1 6 × 10 1 8 × 10 1 2 4 6 8 2 4 6 8 2 4 6 8 S = 10 –8 % S = 10–2 % S = 10 –1 % S = 100% threshold of pain threshold of hearing –20 10 0 Key in air in water ACT-67C-PRACTICE 4 4 END OF TEST 4 STOP! DO NOT RETURN TO ANY OTHER TEST. [See Note on page 54.] 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 53 If you plan to take the ACT Plus Writing, sharpen your pencils and continue with the Writing Test on page 55. If you do not plan to take the ACT Plus Writing, skip to page 57 for instructions on scoring your multiple-choice tests. 54 18263 Preparing ACT 2012-13_5003 AAP Prep for ACT 6/8/12 9:34 AM Page 54