HESI A2 Chemistry

Correct Answer: B

Rationale: The correct answer is B: Amino acids. Proteins are made up of long chains of amino acids, which are the building blocks of proteins. Amino acids are linked together by peptide bonds to form polypeptide chains, which then fold into complex 3D structures to create proteins. Fatty acids (choice A) are lipids, nucleotides (choice C) are the building blocks of nucleic acids like DNA and RNA, and sugars (choice D) are carbohydrates. Therefore, choices A, C, and D are incorrect as they do not make up proteins.

Correct Answer: C

Rationale: The correct answer is C, pink. Phenolphthalein is colorless in acidic solutions and turns pink in the presence of a base due to a shift in pH causing a structural change. This color change is a result of the molecule's ability to act as a pH indicator, making it ideal for titrations. Choice A, clear, is incorrect as phenolphthalein is not colorless in the presence of an acid. Choice B, blue, is incorrect as phenolphthalein does not turn blue in any pH range. Choice D, red, is incorrect as phenolphthalein turns pink, not red, in the presence of a base.

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.

Correct Answer: D

Rationale: The correct answer is D: ionization energy. Ionization energy is the energy needed to remove an electron from an atom. The outermost electron requires the least amount of energy to remove as it is farthest from the nucleus. This process results in the formation of a positively charged ion. Explanation: 1. Covalent bonding (A) refers to the sharing of electrons between atoms, not the energy required to remove an electron. 2. Electronegativity (B) is the ability of an atom to attract electrons in a chemical bond, not the energy needed to remove an electron. 3. Atomic radius (C) is the size of an atom, which does not directly relate to the energy required to remove an electron.

Correct Answer: B

Rationale: Failed to generate a rationale after 5 retries.