HESI A2 Chemistry

Correct Answer: C

Rationale: The correct answer is C: Cl and P. Both chlorine (Cl) and phosphorus (P) are in the same group on the periodic table (Group 7A/17) and therefore have similar outer electron configurations. This results in similar reactivity patterns, such as forming covalent compounds. Choices A, B, and D are incorrect because they involve elements from different groups with different electron configurations and reactivity patterns. He (helium) and H (hydrogen) are both in different groups and have very different properties. K (potassium) and Ar (argon) are from different groups and have different reactivity levels. Ba (barium) and Mg (magnesium) are also from different groups and exhibit different reactivity behaviors.

Correct Answer: B

Rationale: Failed to generate a rationale after 5 retries.

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: 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: B

Rationale: The correct answer is B: Acid. Acids are hydrogen or proton donors, corrosive to metals, turn blue litmus paper red (indicating acidity), and become less acidic when mixed with a base due to neutralization reaction. Bases (choice A) are proton acceptors and do not exhibit these characteristics. Salts (choice C) are formed from the reaction between an acid and a base and do not fit all the given criteria. Hydroxides (choice D) are bases and do not donate protons or exhibit the acidic properties described.