HESI A2 Chemistry

Correct Answer: B

Rationale: The correct answer is B: London dispersion force. This is because London dispersion forces are the weakest intermolecular force, resulting in lower boiling points compared to the other options. London dispersion forces are temporary, induced forces caused by momentary fluctuations in electron distribution within molecules. Dipole-dipole interactions (A), Keesom interactions (C), and hydrogen bonding (D) are stronger intermolecular forces that require specific molecular properties such as permanent dipoles or hydrogen bonding, leading to higher boiling points. Therefore, London dispersion forces would result in the lowest boiling point among the options provided.

Correct Answer: B

Rationale: The correct answer is B (2). In a single covalent bond, two electrons are shared between two atoms to achieve a stable electron configuration. This sharing of electrons allows both atoms to fill their outermost electron shell and achieve a stable, lower energy state. This sharing of two electrons forms a single covalent bond. Explanation for other choices: A (1): One electron sharing would not be sufficient to form a stable covalent bond. C (3) and D (4): These options are incorrect because a single covalent bond involves the sharing of only two electrons, not three or four.

Correct Answer: B

Rationale: Failed to generate a rationale after 5 retries.

Correct Answer: C

Rationale: The correct answer is C: A 5 carbon sugar. Pentose sugars are carbohydrates with 5 carbon atoms. They are essential components of nucleic acids like DNA and RNA. A is incorrect because it has 6 carbons, not 5. B is incorrect as it has 4 carbons. D is incorrect as it has 7 carbons, not 5. Therefore, the correct choice is C as it accurately describes a pentose sugar.

Correct Answer: C

Rationale: The molar mass of sodium chloride (NaCl) is calculated by adding the atomic masses of sodium (Na) and chlorine (Cl) together. Sodium has an atomic mass of approximately 23 g/mol, and chlorine has an atomic mass of approximately 35.5 g/mol. Adding these two values gives a molar mass of 58.5 g/mol for sodium chloride. Rounding to the nearest whole number, the mass of one mole of sodium chloride is 58 g/mol, which corresponds to choice C. Choices A, B, and D are incorrect as they do not accurately reflect the molar mass of sodium chloride. Option A is close but slightly lower than the correct value, while options B and D are significantly off.