Chemistry HESI A2 Quizlet

Correct Answer: A

Rationale: Step-by-step rationale: 1. Combustion of hydrocarbons involves reaction with oxygen. 2. Hydrocarbons contain only carbon and hydrogen atoms. 3. Complete combustion results in the formation of water (H2O) and carbon dioxide (CO2). 4. This is due to the hydrogen atoms combining with oxygen to form water and carbon atoms combining with oxygen to form carbon dioxide. 5. Therefore, the correct answer is A: Water and carbon dioxide. Summary: - Choice B is incorrect as oxygen is not a product of combustion, but a reactant. - Choice C is incorrect as hydrogen and carbon monoxide are not the typical products of hydrocarbon combustion. - Choice D is incorrect as oxygen is not a product of combustion, and carbon monoxide is not a common product of hydrocarbon combustion.

Correct Answer: A

Rationale: The Group IA elements, also known as alkali metals, have a +1 charge. This is because they have one valence electron, which they readily lose to achieve a stable electron configuration. This results in them forming ions with a +1 charge. Therefore, the correct answer is A. Choice B (+2) is incorrect because alkali metals do not typically form ions with a +2 charge due to their tendency to lose only one electron. Choice C (+3) is also incorrect as alkali metals do not form ions with a +3 charge. Choice D (0) is incorrect because alkali metals are known for their tendency to lose electrons to achieve a stable configuration, resulting in a positive charge.

Correct Answer: A

Rationale: The correct answer is A: Stoichiometry. Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. It involves calculating the amount of substances consumed and produced in a reaction based on balanced chemical equations. This includes determining the mole ratios, mass relationships, and volume relationships in a reaction. Choice B (Molecular chemistry) focuses on the structure and properties of molecules, not specifically on quantities in reactions. Choice C (Atomic chemistry) deals with the study of atoms and their properties, not the quantities in reactions. Choice D (Thermodynamics) concerns energy changes in chemical reactions, not the quantitative relationships between compounds. Therefore, stoichiometry is the correct choice for this question.

Correct Answer: A

Rationale: The correct answer is A: Enzyme. Enzymes can act as catalysts in chemical reactions by lowering the activation energy required for the reaction to occur, thereby speeding up the reaction without being consumed in the process. Enzymes are biological molecules that are highly specific to their substrates and can facilitate a wide range of chemical reactions. Explanation for why the other choices are incorrect: B: Light - Light can initiate certain chemical reactions by providing energy, but it is not a catalyst as it is not directly involved in lowering the activation energy. C: Water - Water can be a solvent or participate in chemical reactions, but it does not act as a catalyst by lowering activation energy. D: Metal - Some metals can act as catalysts in certain reactions, but not all metals have catalytic properties, and they do not have the same specificity and efficiency as enzymes in biological systems.

Correct Answer: C

Rationale: The correct answer is C: +2. Alpha radiation particles are helium nuclei consisting of 2 protons and 2 neutrons, giving them a charge of +2. This charge is due to the presence of 2 protons, which are positively charged particles. Choice A (-2) is incorrect as alpha particles are positively charged. Choice B (0) is incorrect as alpha particles have a positive charge. Choice D (+1) is incorrect as alpha particles have a charge of +2 due to the presence of 2 protons.