HESI A2 Version 1 Chemistry

Correct Answer: C

Rationale: An empirical formula represents the simplest whole-number ratio of atoms in a compound. For a hydrocarbon compound consisting of carbon and hydrogen, the empirical formula should have the simplest ratio of carbon to hydrogen. Choice C, 'CH,' is the correct empirical formula as it represents a 1:1 ratio of carbon to hydrogen atoms, indicating the simplest ratio. Choices A, B, and D have multiple atoms of carbon and hydrogen, which do not represent the simplest whole-number ratio. Therefore, 'CH' is the empirical formula that best fits the definition.

Correct Answer: D

Rationale: A combustion reaction is a chemical process that involves a substance reacting with oxygen to produce heat and light. The key component in a combustion reaction is oxygen, making choice D the correct answer. Combustion reactions are typically exothermic, releasing energy in the form of heat and light, making choice A incorrect. Choices B and C describe different types of chemical reactions, not combustion reactions. Therefore, the correct answer is D.

Correct Answer: A

Rationale: The correct answer is A, limiting reactant. In a chemical reaction, the limiting reactant is the substance that is entirely consumed when the reaction reaches completion. It determines the maximum amount of product that can be formed. The reducing agent (choice B) is a substance that donates electrons to another chemical species, the reaction intermediate (choice C) is a molecule formed and consumed in different steps of the reaction, and a reagent (choice D) is a general term for any substance participating in a chemical reaction.

Correct Answer: A

Rationale: The correct name for aqueous HI is hydroiodic acid. In the naming of binary acids, the prefix 'hydro-' is combined with the root of the nonmetal element and the suffix '-ic acid'. Therefore, the correct systematic name for HI in aqueous solution is hydroiodic acid.