Chemistry HESI A2 Practice Test

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: B

Rationale: Failed to generate a rationale after 5 retries.

Correct Answer: A

Rationale: The correct answer is A. Amino acids typically contain an amine group (R-NH2) and a carboxylic acid group (R-COOH). The amine group acts as a base, accepting protons, while the carboxylic acid group acts as an acid, donating protons. This combination allows amino acids to participate in acid-base reactions and form peptide bonds in proteins. Choice B is incorrect because R-CHO is an aldehyde group, not typically found in amino acids. Choice C is incorrect because R-OH is a hydroxyl group and R-COOR is an ester group, neither of which are characteristic functional groups of amino acids. Choice D is incorrect as R-O-R is an ether group, not commonly present in amino acids, and R-COOH alone is not sufficient as amino acids also require an amine group.

Correct Answer: D

Rationale: The correct answer is D: Time. Time does not directly impact rates of reaction; rather, it is the duration over which a reaction occurs. Temperature affects reaction rates by increasing kinetic energy, surface area by exposing more reactant molecules, and pressure by affecting collision frequency. Time is not an influencing factor in itself, but the overall reaction rate may depend on the time taken for the reaction to complete.