HESI A2 Chemistry Practice Test

Correct Answer: C

Rationale: The statement that the volume of a gas is directly proportional to its absolute temperature at constant pressure aligns with Charles' Law. This law states that for a fixed amount of gas at a constant pressure, the volume of the gas is directly proportional to its absolute temperature. As the temperature increases, the volume of the gas also increases proportionally. This relationship is depicted by the equation V1/T1 = V2/T2. The other choices are incorrect because the Combined Gas Law involves pressure, volume, and temperature changes simultaneously; Boyle's Law describes the inverse relationship between pressure and volume at constant temperature, and the Ideal Gas Law is a combination of Boyle's, Charles', and Avogadro's Laws.

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: B

Rationale: The correct answer is B: 6. In sulfuric acid (H2SO4), the oxidation states of hydrogen and oxygen are always +1 and -2, respectively. Since the overall charge of the molecule is 0, the sum of the oxidation states must equal 0. Given that there are two hydrogen atoms (each with an oxidation state of +1) and four oxygen atoms (each with an oxidation state of -2), the oxidation state of sulfur (S) can be calculated as follows: 2(+1) + x + 4(-2) = 0. Solving for x gives x = +6, indicating that the oxidation state of the sulfur atom in sulfuric acid is indeed +6. Summary: A: 4 - Incorrect. This value does not account for the correct oxidation state calculation in sulfuric acid. C: 8 - Incorrect. This value is too high and does not align with the correct oxidation state calculation. D:

Correct Answer: D

Rationale: Boyle's Law states that the pressure of an ideal gas is inversely proportional to its volume when temperature and amount of gas are constant. This can be mathematically expressed as P1V1 = P2V2. As volume decreases, pressure increases and vice versa. Henry's Law relates gas solubility in liquids, Dalton's Law is about partial pressures of gases, and Brown's Law does not exist in the context of ideal gas laws. Thus, the correct answer is D (Boyle's Law).

Correct Answer: B

Rationale: The correct answer is B because glycogen is a type of starch that is primarily found in animals, particularly in their liver and muscles, serving as a storage form of glucose. Plant starches (choice A) are primarily found in plants, not animals. Glucose (choice C) is a simple sugar molecule, not a type of starch. Cellulose (choice D) is a structural polysaccharide found in plant cell walls, not a storage form of glucose like glycogen. Therefore, the correct answer is B, as glycogen is indeed an animal starch.