Chemistry HESI A2 Practice Test

Correct Answer: B

Rationale: The correct answer is B: Amalgam. An amalgam is an alloy where mercury (Hg) is the solvent and another metal is dissolved in it. This is a common dental material. Electrum (A) is a natural alloy of gold and silver. Solder (C) is a metal alloy used to join other metals. Bronze (D) is an alloy of copper and tin.

Correct Answer: B

Rationale: The correct answer is B: Semimetals. These elements exhibit properties of both metals and nonmetals. They are also known as metalloids. B, Si, As, Te, At, Ge, and Sb are located along the staircase pattern on the periodic table, indicating their intermediate nature. They have characteristics like both metals (e.g., conductivity) and nonmetals (e.g., brittleness). Choice A (Metals) is incorrect because these elements do not exhibit all typical metal properties. Choice C (Nonmetals) is incorrect because they do not possess all nonmetal properties exclusively. Choice D (Ultrametals) is not a recognized classification in chemistry.

Correct Answer: C

Rationale: The correct answer is C: Fluorine. Fluorine is not an allotrope of carbon because allotropes are different forms of the same element. Fluorine is a different element altogether. Diamond, graphite, and buckminsterfullerene are all allotropes of carbon, each with unique molecular structures and properties. Diamond has a tetrahedral structure, graphite has layers of hexagonal rings, and buckminsterfullerene has a spherical shape. Fluorine, on the other hand, is a diatomic molecule consisting of two atoms of fluorine bonded together. Therefore, C is the correct answer as it does not belong to the category of carbon allotropes.

Correct Answer: D

Rationale: The correct answer is D: Xe. Xenon (Xe) is a noble gas, meaning it has a full outer electron shell, making it highly stable and least likely to react with other elements. Li (A) is a highly reactive alkali metal, Cr (B) is a transition metal with varying reactivities, and Nd (C) is a rare-earth metal that can exhibit reactivity. In summary, Xe is the least reactive as noble gases tend to be chemically inert due to their stable electron configuration.

Correct Answer: A

Rationale: The correct answer is A: 0 moles. In the given scenario, the volume of the solution is 0 L, which means there is no solution to contain any amount of salt. Molarity is the concentration of a solution in moles of solute per liter of solution. Since the volume is 0 L, there are no moles of salt present. Choice B, C, and D are incorrect because they suggest there are moles of salt present, which is not possible when the volume of the solution is 0 L.