HESI A2 Chemistry Questions

Correct Answer: B

Rationale: The correct answer is B: Fluorine. Fluorine is the most electronegative element because it has the highest electronegativity value on the periodic table. Electronegativity is a measure of an atom's ability to attract and hold onto electrons in a chemical bond. Fluorine has the highest electronegativity value of 3.98, indicating its strong ability to attract electrons. Oxygen (A) is also highly electronegative but has a lower value than fluorine. Nitrogen (C) is less electronegative than oxygen. Sodium (D) is a metal and has low electronegativity compared to the nonmetals listed.

Correct Answer: D

Rationale: The correct answer is D: hydriodic acid. In aqueous solution, HI dissociates into H+ and I- ions, forming hydriodic acid. Choice A (hydroiodic acid) is incorrect as it does not reflect the presence of water in the compound. Choice B (hydrogen monoiodide) is incorrect as it incorrectly implies the presence of only one iodide ion. Choice C (hydrogen iodide) is incorrect as it does not specify the compound in aqueous solution. Therefore, the correct term for aqueous HI is hydriodic acid.

Correct Answer: B

Rationale: The correct answer is B: Solid. In solids, particles are tightly packed in a fixed position due to strong intermolecular forces holding them in place. This results in a definite shape and volume. In liquids (choice A), particles are close together but not in fixed positions, allowing them to flow and take the shape of their container. In gases (choice C), particles are far apart and move freely, leading to indefinite shape and volume. In plasma (choice D), particles are highly energized, ionized, and not bound together, making them not tightly packed or in fixed positions.

Correct Answer: A

Rationale: The correct answer is A: Fluorine. Fluorine has the highest electronegativity because it has the smallest atomic size among the choices, leading to a stronger attraction for electrons. This makes it more likely to attract electrons in a chemical bond. Chlorine, Nitrogen, and Oxygen have lower electronegativities compared to Fluorine due to their larger atomic sizes, resulting in weaker electron-attracting capabilities. Remember, electronegativity generally increases across a period from left to right in the periodic table.

Correct Answer: B

Rationale: The correct answer is B: Ionic bond. Sodium chloride is formed when sodium, a metal, transfers its electron to chlorine, a non-metal, resulting in the formation of Na+ and Cl- ions that are held together by electrostatic forces, forming an ionic bond. In an ionic bond, electrons are transferred from one atom to another, leading to the attraction between oppositely charged ions. Covalent bonds (choice A) involve sharing of electrons between atoms, which is not the case in sodium chloride. Metallic bonds (choice C) involve sharing of electrons in a sea of delocalized electrons within a metal lattice, which is not present in sodium chloride. Hydrogen bonds (choice D) are weaker intermolecular forces that occur between molecules containing hydrogen bonded to highly electronegative atoms like oxygen or nitrogen, which is not relevant to the bonding in sodium chloride.