Chemistry HESI A2 Quizlet

Correct Answer: C

Rationale: The correct answer is C: Speeds up the reaction. A catalyst works by providing an alternative pathway for the reaction to occur with lower activation energy, thus increasing the reaction rate without being consumed in the process. This is achieved by stabilizing the transition state of the reaction, making it easier for the reactants to form products. Choice A is incorrect because a catalyst does not slow down the reaction. Choice B is incorrect as catalysts do have a significant effect on reaction rates. Choice D is incorrect because a catalyst does not stop the reaction; it only affects the rate at which the reaction occurs.

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: Chemical. In chemical reactions, atoms interact to achieve stable electron configurations through sharing, gaining, or losing electrons. This process involves forming chemical bonds to reach a more stable state, following the octet rule. Nuclear reactions involve changes in the nucleus, not electron configurations. Physical reactions involve changes in state or phase, not electron configurations. Mechanical reactions involve forces and motions, not electron configurations. Therefore, the correct choice is A as it directly pertains to atoms achieving stable electron configurations through chemical interactions.

Correct Answer: C

Rationale: The correct answer is C: Radiation. During radioactivity, particles such as alpha and beta particles, gamma rays, and positrons are emitted. These particles are collectively known as radiation. Electrons (choice A) and protons (choice B) are subatomic particles found in atoms and are not typically emitted during radioactivity. Neutrons (choice D) are neutral subatomic particles and are not emitted during radioactivity. Therefore, the correct answer is C as it encompasses the various types of particles emitted during radioactive decay.

Correct Answer: A

Rationale: The correct answer is A: 1. In a single bond, only one pair of electrons is shared between two atoms, resulting in a stable bond. This shared pair of electrons creates a strong attraction between the atoms, holding them together. The other choices (B, C, D) are incorrect as they represent the number of pairs of electrons shared in double, triple, or quadruple bonds, respectively, which involve 2, 3, or 4 pairs of electrons being shared, not in a single bond. Thus, the correct answer is A because a single bond involves only one pair of shared electrons.