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Practice Test 36 - High School Chemistry

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

  1. A student decomposed hydrogen peroxide (H2O2\mathrm{H_2O_2}) using different catalysts. Each trial used 25.0 mL of 3.0% H2O2\mathrm{H_2O_2} at 23.0°C and measured the volume of O2\mathrm{O_2} collected after 60 s. Table: Catalyst vs. O2\mathrm{O_2} volume after 60 s
    CatalystO2\mathrm{O_2} volume (mL)Qualitative observation
    None4Few bubbles
    MnO2_2(s)38Vigorous bubbling
    KI(aq)31Steady bubbling
    Yeast slurry24Foamy bubbles
    Which conclusion is best supported by the data?
  2. Chlorine (Cl, Group 17 Period 3) is bubbled through a solution of potassium bromide (KBr), which contains bromide ions from bromine (Br, Group 17 Period 4). Based on halogen reactivity trends, what should happen?
  3. A hand warmer releases heat through a chemical reaction with ΔH=−150 kJ\Delta H = -150\ \mathrm{kJ}. Which description best matches this enthalpy change?
  4. A museum is choosing a clear cover for a display case containing a reactive metal artifact that tarnishes when exposed to moisture and some airborne chemicals. The cover must be transparent, should not release chemicals that could react with the artifact, and must resist scratching from cleaning. Budget is moderate. Which material is the best trade-off? Options: - Acrylic (PMMA): very clear; relatively scratch-resistant; can crack under impact; generally low chemical outgassing. - Polyvinyl chloride (PVC) sheet: inexpensive; can release plasticizers/additives over time; decent impact resistance. - Polycarbonate: very impact-resistant; can scratch more easily; may require coatings; generally low outgassing but can be more expensive.
  5. The nuclear equation 614C→714N+−10e^{14}_{6}\mathrm{C} \rightarrow {}^{14}_{7}\mathrm{N} + {}^{0}_{-1}\mathrm{e} shows carbon-14 changing into nitrogen-14. What type of radioactive decay is shown?
  6. Balance the chemical equation using the smallest whole-number coefficients (do not change subscripts): CH4 + O2 → CO2 + H2O
  7. Deuterium-tritium fusion can be written as 12H+13H→24He+01n.^{2}_{1}\text{H} + ^{3}_{1}\text{H} \rightarrow ^{4}_{2}\text{He} + ^{1}_{0}\text{n}. Which particle is produced along with helium-4?
  8. A city water-testing club wants to know if adding a small amount of calcium chloride (CaCl2_2) to water causes a chemical change or only dissolving, because CaCl2_2 is used to melt ice and can warm up when mixed with water. Which investigation design best tests whether the process is chemical or physical by planning appropriate evidence collection and controls?
  9. Carbon-14 (C-14) and carbon-12 (C-12) are isotopes of carbon. Which statement correctly compares them?
  10. A student must choose which halogen is least likely to react in a displacement reaction (lowest reactivity as a halogen). The options are chlorine (Cl, Group 17 Period 3), bromine (Br, Group 17 Period 4), and iodine (I, Group 17 Period 5). Which is least reactive?
  11. A food company proposes using food irradiation to reduce bacteria such as Salmonella and extend shelf life without adding chemical preservatives. The process uses a controlled radiation source and requires shielding, trained operators, and strict regulations to prevent unnecessary exposure. Which statement best reflects the trade-offs of food irradiation?
  12. An engineering team proposes storing high-level radioactive waste in a deep geological repository. Benefits include isolating waste from people and the environment and reducing the need for constant surface monitoring. Concerns include ensuring long-term containment for thousands of years, transportation risks, and community acceptance near the site. Which choice best reflects a balanced view?
  13. A city is choosing between building a new nuclear plant or expanding wind and solar. Nuclear power can deliver constant electricity with low greenhouse gas emissions during operation, but it creates long-lived radioactive waste and has low-probability, high-consequence accident risks. Wind and solar avoid radioactive waste but can be intermittent and may require energy storage or backup power. Which choice best evaluates the trade-offs described?
  14. A student claims: "The reaction between baking soda (sodium bicarbonate) and vinegar is endothermic." Evidence observed during one trial: 1) Temperature dropped from 22.0°C to 18.5°C after mixing. 2) Bubbles and foaming were observed. 3) The mixture made a fizzing sound. 4) The beaker felt cold to the touch. 5) The vinegar smelled sour before and after. Which evidence is the strongest and most directly relevant support for the claim?
  15. Wood is placed in a campfire. After several minutes, the wood is gone and there is ash, smoke, and a noticeable release of heat and light. Which type of change is described?
  16. A nuclear submarine can operate for years without refueling, while a diesel-powered ship must refuel frequently. Which explanation best connects this to the difference between nuclear and chemical energy sources?
  17. Nitrogen monoxide forms by N2+O2→2NO.\text{N}_2 + \text{O}_2 \rightarrow 2\text{NO}. If 1.0 mol N2\text{N}_2 reacts with 4.0 mol O2\text{O}_2, what is the maximum amount of NO that can form?
  18. A student burns a 25 g piece of charcoal (carbon) in an open grill. Afterward, only 2 g of ash remains in the grill. Which is the best explanation for the large apparent mass decrease?
  19. A neutral atom has 9 protons and 10 neutrons. Which element is it?
  20. A single-step energy profile is drawn with Energy on the y-axis and Reaction progress on the x-axis. The curve starts at the reactants, rises to one peak, then falls to the products. Which diagram feature shows the overall energy change (ΔH\Delta H)?

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