ACT Past Papers with Answers

Paper 2

ACT December 2024

Form H31 · Science Test · 40 questions

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Paper 2 · ACT December 2024 · Form H31 · Science Test

Based on Table 1, at 36 months after planting, which soil depth—10 cm or 50 cm—had the lower Ca2+ concentration? concentration at a soil depth of 10 cm was 0.2 meq/L less than that at a soil depth of 50 cm. concentration at a soil depth of 10 cm was 0.4 meq/L less than that at a soil depth of 50 cm. concentration at a soil depth of 50 cm was 0.2 meq/L less than that at a soil depth of 10 cm. concentration at a soil depth of 50 cm was 0.4 meq/L less than that at a soil depth of 10 cm. 39 GO ON TO THE NEXT PAGE. ACT-H31 4 4 2. Based on Figure 1, the electrical conductivity for a soil depth of 50 cm at 1 month after planting was approxi- mately how much greater than the electrical conductiv- ity for a soil depth of 10 cm at 36 months after planting?

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Paper 2 · ACT December 2024 · Form H31 · Science Test

Consider the claim “As the soil depth increased from 10 cm to 50 cm and then to 90 cm, the Ca2+ concentra- tion increased and then decreased.” This claim is con- sistent with the data shown in Table 1 for which of 1 month and 24 months after planting, if either? 40 GO ON TO THE NEXT PAGE. ACT-H31 4 4 Passage II Heavy metals in the environment often have concen- trations too low to be detected by common testing methods. Solid phase extraction (SPE) can be used to improve heavy metal detection. Scientists performed 3 SPE experiments to examine the use of graphene (a form of pure carbon) in the analysis of cadmium (a heavy metal) in aqueous samples. Experiment 1 In each trial, a different mass of graphene was added to 0.05 L of a 0.1-micrograms per liter (μg/L) cadmium solution of a specific pH. This sample was incubated in a water bath for 40 min at a specific temperature. The sample was removed from the bath, and the graphene was sepa- rated from the liquid by centrifugation (spinning). The iso- lated graphene was treated with a solution to release the cadmium from the graphene, and then the percent recovery of cadmium was determined. See Figure 1. percent recovery of cadmium 100 80 60 40 20 0 mass of graphene per sample (mg) 0 5 10 15 25 20 30 Figure 1 Experiment 2 Experiment 1 was repeated except that an identical mass of graphene was added to the cadmium solution in each trial and each sample had a different pH. See Figure 2. percent recovery of cadmium 100 80 60 40 20 0 pH 0 1 2 3 5 4 6 7 9 8 Figure 2 Experiment 3 Experiment 1 was repeated except that an identical mass of graphene was added to the cadmium solution in each trial and each sample was incubated at a different temperature. See Figure 3. percent recovery of cadmium 100 80 60 40 20 0 incubation temperature (°C) 20 30 40 50 60 70 Figure 3 Figures adapted from R. Hallaj et al., “Adsorption of Cadmium(II) Ions from Aqueous Solution on Exfoliated Graphene Nanosheets and Its Determination by Flame Atomic Absorption Spectrometry.” ©2014 by NRC Research Press.

A1 month onlyB24 months onlyCBoth 1 month and 24 monthsDNeither 1 month nor 24 months

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Paper 2 · ACT December 2024 · Form H31 · Science Test

Which of the following expressions gives the average surface area of the bread, in square centimeters (cm2 ), covered by R. nigricans for Group C at 72 hr in Experiment 1 ? × 20% × 20% × 78% × 78% 44 GO ON TO THE NEXT PAGE. ACT-H31 4 4 Passage IV Introduction A person is caught in a rainstorm. The person must travel westward along a straight path for a particular dis- tance, L, in order to reach a shelter. Based on the number of raindrops falling on the person per second, N, and the total number of raindrops, S, that fall on the person while traveling the distance L, each of 4 students discusses whether the person should walk or run. The 4 students are given Figure 1 and the list of information that follows Figure 1. west down shelter speed of raindrops path vw −vd direction of raindrops u L Figure 1 • The rain is falling downward and to the west. The inten- sity of the rainfall—the number of drops per second striking each square meter of ground—is constant. • The velocity of any given raindrop has both a downward vertical component, −vdown (or −vd), and a westward hor- izontal component, vwest (or vw). Both components are constant, and vw is parallel to the path. • The person’s speed is represented by the symbol u. • The time required for the person to travel the distance L is represented by the symbol t. Student 1 The person should walk. Time t will be greater if the person walks than if the person runs, but N will be less, so S will be less. Student 2 The person should run, because N will be less than if the person walks. Moreover, both t and S will be less than if the person walks because the person will spend less time in the rain. Student 3 The person’s speed should equal vw. At that speed, both N and S will have their minimum values, so both N and S will be smaller than if the person moves at a different speed. Student 4 S will be approximately the same whether the person walks or runs. N will be less if the person walks than if the person runs, but t will be greater. N will be greater if the person runs, but t will be less.

Aπ × (2.5 cm)2Bπ × (5.0 cm)2Cπ × (2.5 cm)2Dπ × (5.0 cm)2

Form H31 · Science Test · 40 questions

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