Chemistry HESI A2 Quizlet

Correct Answer: A

Rationale: The correct answer is A because a balanced chemical equation must satisfy the law of conservation of mass. This means that the number of atoms of each element must be the same on both the reactant and product sides. This ensures that no atoms are gained or lost during a chemical reaction. Explanation for why the other choices are incorrect: B: An equation with more products than reactants does not follow the law of conservation of mass. C: Balancing the number of molecules is important, but the key factor is balancing the number of atoms of each element. D: Equal masses on both sides do not necessarily guarantee that the number of atoms of each element is the same.

Correct Answer: B

Rationale: The correct answer is B: 0. Noble gases have a full outer electron shell, making them stable and unreactive. This full shell means they do not gain or lose electrons, so they have no overall charge, making their charge 0. Choice A (-1) is incorrect because it indicates gaining an electron to achieve a full outer shell, which is not characteristic of noble gases. Choices C (1) and D (2) are incorrect as they suggest a positive charge, which noble gases do not possess due to their stable electron configuration.

Correct Answer: D

Rationale: Dispersion forces are the weakest intermolecular force because they are caused by temporary fluctuations in electron distribution, leading to temporary dipoles. These forces exist between all molecules, regardless of polarity. Dipole interactions are stronger as they involve permanent dipoles in polar molecules. Hydrogen bonding is even stronger, occurring between a hydrogen atom bonded to a highly electronegative atom and another electronegative atom. Van der Waals forces encompass both dipole interactions and dispersion forces. Thus, dispersion forces are the weakest intermolecular force among the given options.

Correct Answer: B

Rationale: The correct answer is B: Nuclear. Nuclear reactions involve changes in the nucleus of an atom, such as nuclear fusion or fission, to achieve stable nuclear configurations by balancing the number of protons and neutrons. Chemical reactions (Choice A) involve changes in electron configurations, not the nucleus. Physical reactions (Choice C) involve changes in state or structure, not nuclear configurations. Mechanical reactions (Choice D) involve forces and motion, not changes in the nucleus for stability. Therefore, option B is the correct choice for reactions taking place in the nucleus to achieve stable nuclear configurations.

Correct Answer: B

Rationale: The correct answer is B: Single replacement. In this type of reaction, an active metal replaces another metal in an ionic compound, forming a new compound. This is due to the reactivity of the active metal displacing the less reactive metal in the compound. Combustion (choice A) involves a substance reacting with oxygen to produce heat and light. Synthesis (choice C) is the combination of two or more substances to form a new compound. Decomposition (choice D) is when a compound breaks down into simpler substances. In this scenario, single replacement best fits the description of an active metal reacting with an ionic compound to create a new compound.