Chemistry HESI A2 Practice Test

Questions 33

HESI A2

HESI A2 Test Bank

Chemistry HESI A2 Practice Test Questions

Question 1 of 5

Which of the following factors would not affect rates of reaction?

Correct Answer: D

Rationale: The correct answer is D: Time. Time does not directly impact rates of reaction; rather, it is the duration over which a reaction occurs. Temperature affects reaction rates by increasing kinetic energy, surface area by exposing more reactant molecules, and pressure by affecting collision frequency. Time is not an influencing factor in itself, but the overall reaction rate may depend on the time taken for the reaction to complete.

Question 2 of 5

How many times more acidic is a substance with a pH of 3 compared to a substance with a pH of 5?

Correct Answer: D

Rationale: To determine how many times more acidic a substance is based on pH, we use the formula: times more acidic = 10^(pH difference). In this case, the pH difference is 3 - 5 = -2. So, times more acidic = 10^(-2) = 1/1000. Therefore, a substance with a pH of 3 is 1,000 times more acidic than a substance with a pH of 5. Choice A (8) is incorrect because it does not reflect the pH difference between 3 and 5. Choice B (2) is incorrect as it does not consider the logarithmic scale of pH. Choice C (100) is incorrect as it does not accurately calculate the pH difference and the corresponding acidity factor.

Question 3 of 5

Radioactive isotopes are frequently used in medicine. What kind of half-life would a medical isotope probably have?

Correct Answer: B

Rationale: The correct answer is B: Days-long. Medical isotopes used in medicine typically have a short half-life to minimize radiation exposure to patients. A days-long half-life strikes a balance between decay rate and practical usability in medical procedures. Choice A (Seconds-long) would be too short for practical use. Choices C (Years-long) and D (Many years long) would result in prolonged radiation exposure, increasing health risks for patients.

Question 4 of 5

On what concept is Kelvin based?

Correct Answer: B

Rationale: The correct answer is B: Absolute zero. Kelvin is based on the concept of absolute zero, which is the coldest possible temperature where particles have minimal kinetic energy. This forms the foundation for the Kelvin temperature scale. A: Freezing point is incorrect because Kelvin is not specifically based on the freezing point of any substance. C: Boiling point is incorrect as Kelvin is not directly linked to the boiling point of any substance. D: Evaporation point is incorrect because Kelvin does not relate to the point at which a substance undergoes evaporation.

Question 5 of 5

Which element would you expect to be least reactive?

Correct Answer: D

Rationale: The correct answer is D: Xe. Xenon (Xe) is a noble gas, meaning it has a full outer electron shell, making it highly stable and least likely to react with other elements. Li (A) is a highly reactive alkali metal, Cr (B) is a transition metal with varying reactivities, and Nd (C) is a rare-earth metal that can exhibit reactivity. In summary, Xe is the least reactive as noble gases tend to be chemically inert due to their stable electron configuration.

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