HESI A2
Chemistry HESI A2 Practice Test
1. What is the normal body temperature in Fahrenheit?
- A. 96°F
- B. 98.6°F
- C. 100°F
- D. 95°F
Correct answer: B
Rationale: The normal body temperature for humans is 98.6°F, which is equivalent to 37°C. This temperature is considered the average baseline for most individuals when measured orally. Choice A (96°F) is too low for normal body temperature. Choice C (100°F) is too high for normal body temperature. Choice D (95°F) is also lower than the normal body temperature range. Therefore, the correct answer is B, 98.6°F.
2. What is the pH of acids?
- A. 7.5
- B. < 7
- C. > 7
- D. 7
Correct answer: B
Rationale: The correct answer is B: < 7. Acids have a pH lower than 7, indicating higher acidity. A pH below 7 signifies an acidic solution, with lower values indicating stronger acids. Choice A (7.5) is incorrect as it is greater than 7, which is alkaline. Choice C (> 7) is incorrect as values greater than 7 represent alkaline/basic solutions. Choice D (7) is incorrect because a pH of 7 is neutral, not acidic.
3. What is the typical oxidation state of oxygen in most compounds?
- A. -1
- B. -2
- C. 0
- D. -3
Correct answer: B
Rationale: The correct answer is B: "-2". Oxygen usually exhibits an oxidation state of -2 in most compounds. This is due to oxygen's high electronegativity, which causes it to attract electrons, leading to the gain of two electrons in chemical reactions. Choice A (-1) is incorrect because oxygen rarely has an oxidation state of -1 in compounds. Choice C (0) is incorrect as oxygen does not usually have an oxidation state of zero in compounds. Choice D (-3) is incorrect as oxygen does not commonly have an oxidation state of -3 in compounds.
4. If gas A has four times the molar mass of gas B, you would expect it to diffuse through a plug ___________.
- A. at half the rate of gas B
- B. at twice the rate of gas B
- C. at a quarter the rate of gas B
- D. at four times the rate of gas B
Correct answer: A
Rationale: When comparing the diffusion rates of two gases, according to Graham's law of diffusion, the rate of diffusion is inversely proportional to the square root of the molar mass. If gas A has four times the molar mass of gas B, the square root of the molar masses ratio (4:1) is 2. This means that gas A would diffuse through a plug at half the rate of gas B. Therefore, the correct answer is A, at half the rate of gas B. Choices B, C, and D are incorrect because they do not reflect the correct relationship between the molar masses and the rates of diffusion according to Graham's law.
5. Which of the following factors would not affect rates of reaction?
- A. Temperature
- B. Surface area
- C. Pressure
- D. Time
Correct answer: D
Rationale: Time would not directly affect rates of reaction. The rate of a chemical reaction is determined by factors that affect the frequency of successful collisions between reactant molecules, leading to a reaction. Temperature, surface area, and pressure can influence reaction rates by impacting the kinetic energy of molecules, the exposed surface for collisions, and the concentration of reactants, respectively. However, time, in the context of this question, does not alter the rate of reaction but may affect the extent of the reaction or the amount of product formed over time.
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