HESI A2 Chemistry

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.

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: 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: The correct answer is B (-1) because in NaOH, Na is a group 1 metal with an oxidation state of +1, and H is typically +1. Since the compound is neutral, the oxidation state of oxygen must be -1 to balance the charges. Choice A (-2) is incorrect because oxygen rarely has an oxidation state of -2 in compounds. Choice C (0) is incorrect as oxygen is not in its elemental form. Choice D (+2) is incorrect as it is not a common oxidation state for oxygen in compounds.

Correct Answer: C

Rationale: The correct answer is C: Between 6 and 8. Tap water is typically slightly alkaline, with a pH range between 6.5 and 8.5. This is considered neutral to slightly basic, as pure water has a pH of 7. The pH scale ranges from 0 to 14, with 7 being neutral. Choices A, B, and D are incorrect because tap water is not highly acidic (A), acidic (B), or highly alkaline (D). Tap water falls within the slightly basic range on the pH scale.