HESI A2 Chemistry Practice Test

Correct Answer: A

Rationale: Rationale: A is false because in an endothermic process, solubility usually increases with increasing temperature and decreases with decreasing temperature due to the absorption of heat. B is true, as solubility generally decreases with increasing temperature in exothermic processes. C and D are incorrect as A is false.

Correct Answer: B

Rationale: The typical oxidation state of oxygen in most compounds is -2. Oxygen is highly electronegative and tends to gain 2 electrons to achieve a stable octet configuration. This results in an oxidation state of -2 in compounds like water (H2O) and carbon dioxide (CO2). Therefore, choice B is correct. Choice A (-1) is incorrect because oxygen rarely has an oxidation state of -1 in compounds. Choice C (0) is incorrect as oxygen doesn't usually have an oxidation state of 0; it prefers to gain electrons. Choice D (-3) is incorrect as it is an uncommon oxidation state for oxygen in compounds.

Correct Answer: C

Rationale: The correct answer is C: Boyle. Boyle's Law states that the pressure and volume of a gas are inversely proportional when temperature is constant. Boyle conducted experiments that led to this discovery. Choice A, Charles, is known for Charles's Law which relates volume and temperature. Choice B, Combine, is not a known scientist. Choice D, Gay-Lussac, is known for Gay-Lussac's Law which relates pressure and temperature.

Correct Answer: B

Rationale: The correct answer is B. Temperature affects reaction rates by increasing kinetic energy. Particle size influences surface area available for collision. Concentration impacts frequency of collisions. Catalysts lower activation energy. Barometric pressure, container material, elevation, and volatility do not directly affect reaction rates. Option A includes "barometric pressure" and "facilitator," which are irrelevant. Option C includes "container material" and "elevation," which are not factors. Option D includes "volatility," which is not typically a factor in rates of reaction.

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.