Chemistry HESI A2 Practice Test

Correct Answer: A

Rationale: To balance the equation, count the number of O atoms on both sides. If the equation is balanced, the coefficient of O should be the same on both sides. In this case, the coefficient of O is already 1 on both sides (since O appears only once on each side), so the correct answer is A. Choices B, C, and D are incorrect because changing the coefficient of O to any of those values would unbalance the equation.

Correct Answer: A

Rationale: The correct answer is A: 0 moles. In the given scenario, the volume of the solution is 0 L, which means there is no solution to contain any amount of salt. Molarity is the concentration of a solution in moles of solute per liter of solution. Since the volume is 0 L, there are no moles of salt present. Choice B, C, and D are incorrect because they suggest there are moles of salt present, which is not possible when the volume of the solution is 0 L.

Correct Answer: B

Rationale: The correct answer is B: < 7. Acids have a pH below 7 because they release hydrogen ions when dissolved in water, making the solution acidic. A pH of 7 is neutral, not acidic. Choices A (7.5) and C (> 7) are incorrect because they indicate values above 7, which would be alkaline/basic. Choice D (7) is incorrect because it represents a neutral pH, not acidic. Thus, the correct answer is B as it accurately represents the pH range of acids.

Correct Answer: A

Rationale: The correct answer is A (pH 3) for lemon juice. Lemon juice is acidic due to citric acid content, resulting in a low pH value. The pH scale ranges from 0-14, with 7 being neutral. Lemon juice with a pH of 3 is considered highly acidic. Choice B (pH 5) is less acidic than choice A. Choice C (pH 7) is neutral, which is not characteristic of lemon juice. Choice D (pH 9) is alkaline, opposite to the acidity of lemon juice. Lemon juice's low pH value contributes to its sour taste and preservation properties.

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.