Chemistry HESI A2 Practice Test

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: 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: B

Rationale: The correct answer is B: 8. Carbon-14 has 6 protons, so to find the number of neutrons, subtract the atomic number from the atomic mass. Carbon-14 has an atomic mass of approximately 14, so 14 (atomic mass) - 6 (protons) = 8 neutrons. Choice A (10) is incorrect because it doesn't correspond to the correct calculation for carbon-14. Choice C (6) is the number of protons, not neutrons. Choice D (12) is incorrect as it does not align with the calculated number of neutrons in carbon-14.

Correct Answer: A

Rationale: The correct answer is A: 92. Uranium-235 has an atomic number of 92, which represents the number of protons in its nucleus. Neutrons are calculated by subtracting the atomic number from the mass number (235 - 92 = 143), so there are 143 neutrons in uranium-235. This makes option A the correct choice. Options B, C, and D are incorrect because they do not accurately reflect the number of neutrons in uranium-235 based on its atomic number and mass number.

Correct Answer: D

Rationale: Step 1: Define hydrogen bonding as a special type of dipole-dipole interaction. Step 2: Highlight that hydrogen bonding occurs between a hydrogen atom and highly electronegative atom (N, O, or F). Step 3: Emphasize that hydrogen bonding is stronger due to the large electronegativity difference between hydrogen and the other atom. Step 4: Compare the strength of hydrogen bonding to the other types of intermolecular forces. Step 5: Conclude that hydrogen bonding is the strongest intermolecular force due to its specific characteristics and stronger attraction compared to dipole-dipole interaction, London dispersion force, and Keesom interaction.