Chemistry HESI A2 Practice Test

Correct Answer: C

Rationale: The correct answer is C: +2. An alpha particle consists of two protons and two neutrons, giving it a total charge of +2. Protons have a charge of +1 each, and neutrons have no charge. Therefore, the total charge of an alpha particle is +2. Choice A (-1) is incorrect because it is the charge of an electron. Choice B (+1) is incorrect because it represents the charge of a proton. Choice D (No charge) is incorrect because alpha particles have a positive charge due to the presence of protons.

Correct Answer: D

Rationale: The correct name of AgNO₃ is Silver nitrate (D) because it follows the naming conventions for ionic compounds. "Silver" is the cation (Ag⁺) and "nitrate" is the anion (NO₃⁻), so the compound is named as "Silver nitrate." A: Argent nitrous - Incorrect, "argent" refers to silver but "nitrous" is incorrect for the nitrate ion. B: Argent oxide - Incorrect, "oxide" refers to O²⁻ ion, not NO₃⁻. C: Silver nitrite - Incorrect, "nitrite" is different from "nitrate," so the name is incorrect.

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.

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.

Correct Answer: B

Rationale: The correct answer is B: 8. Carbon-14 has 6 protons, so to find the number of neutrons, subtract the atomic number from the atomic mass. Carbon-14 has an atomic mass of approximately 14, so 14 (atomic mass) - 6 (protons) = 8 neutrons. Choice A (10) is incorrect because it doesn't correspond to the correct calculation for carbon-14. Choice C (6) is the number of protons, not neutrons. Choice D (12) is incorrect as it does not align with the calculated number of neutrons in carbon-14.