HESI A2 Chemistry Practice Test

Correct Answer: B

Rationale: The correct answer is B because an amphoteric substance can both donate and accept protons, making it capable of acting as both an acid and a base depending on the reaction it is involved in. Choices A, C, and D are incorrect because they present limited definitions that do not encompass the dual nature of amphoteric substances. A and C are too restrictive, focusing on only one aspect of the substance's behavior, while D is entirely inaccurate as amphoteric substances can indeed act as both a base and an acid.

Correct Answer: C

Rationale: Henry's Law states that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid (P = kC). This means that as the partial pressure of the gas increases, the amount of gas that dissolves in the liquid also increases. This relationship is specifically for gases and volatile substances in liquids. Boyle's Law relates pressure and volume, Gay-Lussac's Law relates pressure and temperature, and Charles' Law relates volume and temperature. Therefore, the correct answer is C, Henry's Law, because it directly describes the relationship between gas solubility and partial pressure.

Correct Answer: A

Rationale: The correct answer is A: Covalent bonds. Covalent bonds involve a complete sharing of electrons between atoms with partially filled outer shells. This sharing allows atoms to achieve stable electron configurations. Hydrogen bonds involve an electrostatic attraction between a hydrogen atom and a highly electronegative atom. Proportional bonds are not a recognized type of chemical bond. Choice D, N/A, is not a valid option for this question.

Correct Answer: A

Rationale: The correct answer is A: A higher concentration of reactants causes more effective collisions per unit time, leading to an increased reaction rate. This is because a higher concentration means there are more reactant molecules in a given volume, increasing the chances of collisions between them. With more collisions occurring, the likelihood of effective collisions (those with sufficient energy and correct orientation) also increases, resulting in a faster reaction rate. Choices B, C, and D are incorrect: B: A lower concentration of reactants causes fewer effective collisions per unit time, leading to a decreased reaction rate - This is incorrect as lower concentration reduces the number of collisions, including effective collisions, hence decreasing the reaction rate. C: A higher concentration of reactants causes more effective collisions per unit time, leading to a decreased reaction rate - This is contradictory and illogical as a higher concentration increasing effective collisions would logically lead to an increased reaction rate. D: A higher concentration of reactants causes fewer effective collisions per unit time, leading

Correct Answer: A

Rationale: The correct answer is A because at high pressure and high temperature, real gases have increased kinetic energy and are closer together, leading to decreased intermolecular forces. This results in gas molecules behaving more like ideal gases with negligible volume and no intermolecular interactions. Choice B is incorrect because at low pressure, real gases have low kinetic energy and are far apart, causing intermolecular forces to become more significant, deviating from ideal behavior. Choice C is incorrect as the boiling point of water is a specific condition related to water and does not necessarily indicate ideal gas behavior. Choice D is incorrect because under certain conditions of high pressure and high temperature, real gases can approach ideal behavior, demonstrating that real gases can exhibit ideal behavior under specific circumstances.