HESI A2 Chemistry

Correct Answer: B

Rationale: The correct answer is B (-1) because in NaOH, Na is a group 1 metal with an oxidation state of +1, and H is typically +1. Since the compound is neutral, the oxidation state of oxygen must be -1 to balance the charges. Choice A (-2) is incorrect because oxygen rarely has an oxidation state of -2 in compounds. Choice C (0) is incorrect as oxygen is not in its elemental form. Choice D (+2) is incorrect as it is not a common oxidation state for oxygen in compounds.

Correct Answer: B

Rationale: The correct answer is B (2). In a single covalent bond, two electrons are shared between two atoms to achieve a stable electron configuration. This sharing of electrons allows both atoms to fill their outermost electron shell and achieve a stable, lower energy state. This sharing of two electrons forms a single covalent bond. Explanation for other choices: A (1): One electron sharing would not be sufficient to form a stable covalent bond. C (3) and D (4): These options are incorrect because a single covalent bond involves the sharing of only two electrons, not three or four.

Correct Answer: B

Rationale: Failed to generate a rationale after 5 retries.

Correct Answer: B

Rationale: To prepare a 0.100 M solution, we use the formula M1V1 = M2V2. Given M1=concentration of concentrated HCl, V1=volume of concentrated HCl, M2=desired concentration, V2=final volume. Plugging in the values, we get M1(unknown volume) = 0.100 M x 500 mL. Solving for the unknown volume, we find V1 = (0.100 M x 500 mL) / M1. As we want to find the volume of concentrated HCl needed, we isolate V1. Therefore, V1 = 100 mL. This corresponds to choice B as the correct answer. Choices A, C, and D are incorrect as they do not match the calculated volume needed to prepare the 0.100 M HCl solution.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Nonmetals are elements that lack metallic properties. 2. Sulfur is a nonmetal as it exists in a gaseous form at room temperature, lacks luster, and is a poor conductor of heat and electricity. 3. Mercury (A) is a metal as it is a liquid at room temperature. 4. Magnesium (B) and Potassium (D) are both metals as they are solid at room temperature and exhibit typical metallic properties. Summary: - A: Mercury is a metal. - B: Magnesium is a metal. - C: Sulfur is the correct answer as a nonmetal. - D: Potassium is a metal.