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Practice Test 12 - ACT Science

20 questions. Answer them in any order, then submit to see your score and every explanation.

  1. Based on the pattern in Table 1, at about what time will the next high tide occur?
  2. An environmental engineer tested whether a filter (Filter Q) removes lead from water. A water sample containing dissolved lead was split into two equal portions. One portion was passed through Filter Q; the other was not filtered. Lead concentration was measured before and after. Based on the data, which conclusion is most strongly supported?
  3. A sports scientist tested whether caffeine improves sprint performance. Sixteen athletes completed a 200 m sprint after consuming either caffeine (3 mg/kg) or a placebo in a crossover design one week apart. However, all athletes received caffeine in Week 1 and placebo in Week 2. Weather differed: Week 1 had a tailwind; Week 2 had no wind. Which statement best evaluates the validity of the author's conclusion that "Caffeine caused faster sprint times"?
  4. A public health team studies why a new respiratory virus spreads rapidly in some indoor workplaces but not others. Three scientists propose explanations. Scientist 1: Scientist 1 argues that ventilation rate is the main driver. Higher air exchange dilutes airborne virus particles, lowering infection probability. Scientist 1 predicts that increasing ventilation (or adding HEPA filtration) will reduce transmission even if employees continue meeting in person. Scientist 2: Scientist 2 argues that close-contact networks drive spread. Transmission occurs mainly through repeated close interactions among the same people, so workplace layout and social grouping matter most. Scientist 2 predicts that reorganizing teams to reduce repeated close contacts will reduce spread even without improving ventilation. Scientist 3: Scientist 3 argues that surface contamination is the key route. People touch shared objects and then touch their faces. Scientist 3 predicts that frequent disinfection and reduced sharing of tools will lower infections even if ventilation and contact patterns remain unchanged. Which statement is consistent with Scientist 1's viewpoint but not Scientist 2's?​​
  5. Up to which charging time does the model match the measurements?
  6. In a calorimetry experiment, if the calorimeter is not properly insulated, the measured heat change would most likely:
  7. Consider the solubility trend of Oxygen gas shown in Figure 2. If the temperature of a lake increases from 20°C to 40°C due to thermal pollution, the amount of dissolved oxygen available to fish would likely:
  8. A student investigated how the number of paper towel layers affects water absorption. She cut paper towels into identical 10 cm×10 cm10\text{ cm} \times 10\text{ cm} squares and stacked them to make pads with 1, 2, 3, or 4 layers. She poured exactly 50 mL of water onto each pad placed in the same type of tray. After 60 seconds, she measured how much water remained in the tray (in mL) and calculated water absorbed by the pad. All trials used the same brand of paper towel and were performed at room temperature. Which of the following is the independent variable?
  9. A student examined whether fertilizer amount changes the number of flowers produced by marigold plants. She grew identical seedlings in 12 identical pots with the same soil type. Pots were assigned to receive 0 g, 5 g, 10 g, or 15 g of fertilizer per week (3 pots per group). All plants received the same volume of water each day, were kept in the same greenhouse with the same light schedule, and were grown for 6 weeks. At the end, she counted the number of flowers on each plant. Which factor was controlled in this experiment?
  10. A botanist studied the effect of water frequency on plant health. Plants were watered daily, weekly, or not at all, and health was assessed. The primary purpose of this experiment was to:
  11. The consistency of results in a viscosity measurement experiment would most likely be affected by:
  12. Based on Table 2, what is the relationship between body mass and metabolic rate per gram for lizards?
  13. A lab tested whether a disinfectant (Solution D) reduces bacterial growth on countertops. Identical countertop squares were inoculated with bacteria and then treated with either Solution D or water (Control). After 4 hours, technicians counted colony-forming units (CFU). The experiment was repeated at two room humidities. Based on the data, which conclusion is most strongly supported?
  14. A chemist investigated how temperature affects the rate of a reaction that produces gas. The same concentrations of reactants were used each time. The chemist measured the time required to produce 50 mL of gas at three temperatures. Based on the data, which conclusion is most strongly supported?
  15. Based on Figure 1, which column is the control?
  16. A study aimed to find the effect of exercise duration on weight loss. Participants engaged in different lengths of exercise routines while their diet and sleep were kept constant. The change in weight was recorded. Which is the dependent variable?
  17. An experiment is conducted to test the effect of air pressure on sound speed. The independent variable is air pressure, and the dependent variable is the speed of sound. Which change would make the experiment more reliable?
  18. A student tested the hypothesis that increasing salt concentration lowers the freezing point of water. She prepared 4 beakers, each with 100 mL of distilled water, and added NaCl to reach concentrations of 0%, 2%, 4%, or 6% (mass/volume). Each beaker was placed in the same freezer set to −10∘C-10^\circ\text{C} for 45 minutes. The student stirred each beaker for 10 seconds every 5 minutes using the same stirring rod and then recorded the temperature at which the first ice crystals appeared (freezing point). All beakers were identical and started at 20∘C20^\circ\text{C}. Which of the following is the independent variable?
  19. Two hypotheses explain the increase in jellyfish populations. Hypothesis 1 states warmer ocean temperatures increase jellyfish numbers. Hypothesis 2 suggests overfishing of predators is the cause. Data correlates higher jellyfish numbers with warmer temperatures. Which hypothesis is more supported?
  20. Based on the chemical equation provided in the Introduction, the bubbles counted in these experiments consisted primarily of:

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