HESI A2 Chemistry Practice Test

Correct Answer: B

Rationale: The correct answer is B: Alloys. Alloys are mixtures of 2 or more metals, where the metals are evenly distributed at a microscopic level. This creates unique properties different from the individual metals. Solutions (A) involve a solute dissolved in a solvent, not necessarily metals. Compounds (C) are formed by chemical bonding between elements, not just a mixture. Suspensions (D) are mixtures where particles are suspended in a fluid but eventually settle out, unlike alloys which are uniform mixtures.

Correct Answer: B

Rationale: The correct answer is B: Alloys. Alloys are mixtures of 2 or more metals, where the metals are evenly distributed at a microscopic level. This creates unique properties different from the individual metals. Solutions (A) involve a solute dissolved in a solvent, not necessarily metals. Compounds (C) are formed by chemical bonding between elements, not just a mixture. Suspensions (D) are mixtures where particles are suspended in a fluid but eventually settle out, unlike alloys which are uniform mixtures.

Correct Answer: B

Rationale: Dalton's law states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases. In the given equation, Ptot = Pa + Pb, it directly represents Dalton's law where Ptot is the total pressure and Pa and Pb are component pressures. This equation shows that the total pressure is the sum of the pressures contributed by each gas in the mixture. Therefore, choice B is correct. Henry's law deals with the solubility of a gas in a liquid, not the relationship between the total and partial pressures of gases in a mixture (Choice A). Boyle's law relates pressure and volume of a gas at constant temperature, not the total and partial pressures of gases in a mixture (Choice C). Gay-Lussac's law describes the relationship between pressure and temperature of a gas at constant volume, not the total and partial pressures of gases in a mixture (Choice D).

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.

Correct Answer: A

Rationale: Correct Answer: A Rationale: 1. pH is a measure of hydrogen ion concentration in a solution. 2. The formula for pH is pH = - log[H+]. 3. This formula indicates an inverse logarithmic relationship between pH and H+ concentration. 4. The effective concentration of hydrogen ions directly influences pH. 5. The molarity of H+ ions is crucial in determining the pH value of a solution. Summary: Choice A is correct as it accurately describes the relationship between pH and hydrogen ion concentration, supported by the logarithmic formula. Choices B, C, and D are incorrect as they misinterpret the role of pH and its relationship to hydrogen ions in a solution.