Chemistry HESI A2 Practice Test

Correct Answer: C

Rationale: The correct answer is C: Polar covalent and ionic. When an acid reacts with a base, water and a salt are produced. In water, the bonds between hydrogen and oxygen are polar covalent due to the electronegativity difference between the two atoms. In the salt formed, the bond between the cation and anion is ionic, as one atom donates electrons to the other, resulting in a strong electrostatic attraction. Choice A (Liquid and metallic) is incorrect as it does not describe the bonds formed in water and the salt. Choice B (Polar and nonpolar covalent) is incorrect because nonpolar covalent bonds do not form in this scenario. Choice D (Ionic only) is incorrect because water forms polar covalent bonds, in addition to the ionic bonds in the salt.

Correct Answer: C

Rationale: The correct answer is C: +2. An alpha particle consists of two protons and two neutrons, giving it a total charge of +2. Protons have a charge of +1 each, and neutrons have no charge. Therefore, the total charge of an alpha particle is +2. Choice A (-1) is incorrect because it is the charge of an electron. Choice B (+1) is incorrect because it represents the charge of a proton. Choice D (No charge) is incorrect because alpha particles have a positive charge due to the presence of protons.

Correct Answer: A

Rationale: The correct answer is A (pH 3) for lemon juice. Lemon juice is acidic due to citric acid content, resulting in a low pH value. The pH scale ranges from 0-14, with 7 being neutral. Lemon juice with a pH of 3 is considered highly acidic. Choice B (pH 5) is less acidic than choice A. Choice C (pH 7) is neutral, which is not characteristic of lemon juice. Choice D (pH 9) is alkaline, opposite to the acidity of lemon juice. Lemon juice's low pH value contributes to its sour taste and preservation properties.

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.

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.