Chemistry HESI A2 Practice Test - Nurselytic

Correct Answer: B

Rationale: The correct answer is B: 8. Carbon-14 is an isotope of carbon with 6 protons and 8 neutrons.
To determine the number of neutrons in an atom, subtract the atomic number (number of protons) from the mass number. In this case, the mass number of carbon-14 is 14, and the atomic number of carbon is 6.
Therefore, 14 (mass number) - 6 (atomic number) = 8 neutrons.

Choices A, C, and D are incorrect because they do not reflect the correct number of neutrons in a carbon-14 atom.

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.

Correct Answer: A

Rationale: Lemon juice is highly acidic with a pH around 2-3, making it more acidic than neutral substances. A pH of 5 is too high for lemon juice, indicating less acidity. Similarly, pH 7 is neutral, and pH 9 would be alkaline, which is not characteristic of lemon juice.
Therefore, the correct answer is option A (pH 3).

Correct Answer: B

Rationale: In the compound HCl (hydrochloric acid), the hydrogen atom has an oxidation state of +1 based on the rules of assigning oxidation states. Since the overall compound is neutral, the oxidation state of chlorine must be -1 to balance the charge. Chlorine typically has an oxidation state of -1 in binary compounds with nonmetals, such as HCl.
Therefore, the correct answer is -1.

Choices A, C, and D are incorrect as the oxidation state of chlorine in HCl is -1, not +1, +2, or -2.

Correct Answer: C

Rationale: The number of protons in the atomic nucleus of an alkali metal is 11. Alkali metals, belonging to group 1 of the periodic table, have 1 electron in their outer shell, which corresponds to 1 proton in their nucleus.
Therefore, the correct answer is option C: 11.
Choice A (9) is incorrect because it does not match the number of protons in an alkali metal.
Choice B (10) is incorrect as it is also not the correct number of protons for an alkali metal.
Choice D (12) is incorrect as it is not the typical number of protons found in the nucleus of an alkali metal.