Chemistry HESI A2 Quizlet

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.

Correct Answer: B

Rationale: The correct answer is B: Solid. Solids have a definite shape and volume because the particles are closely packed and vibrate in fixed positions. Liquids (choice A) have a definite volume but not a definite shape as they take the shape of their container. Gases (choice C) have neither a definite shape nor volume as their particles are free to move around. Plasma (choice D) is a state of matter where particles are ionized, and it lacks a definite shape or volume. Therefore, the correct answer is B.

Correct Answer: B

Rationale: The correct answer is B: Physical. When no change is made to the chemical composition of a substance, it indicates a physical change. In physical changes, the substance retains its chemical identity and only its physical properties, such as shape, size, and state, are altered. This is because the particles in the substance rearrange or move without forming new substances. Choice A (Chemical) involves a change in the chemical composition, so it is incorrect. Choice C (Nuclear) involves changes at the atomic level, leading to different elements, which is not the case here. Choice D (Mechanical) involves changes in position and motion of objects, not relevant to the chemical composition of a substance.

Correct Answer: B

Rationale: The correct answer is B: Double replacement. In this type of reaction, two ionic compounds swap ions to form two new compounds. The cations and anions switch partners, leading to the formation of two different ionic compounds. This process is also known as metathesis. Single replacement (A) involves an element replacing another in a compound. Synthesis (C) involves the combination of two or more substances to form a single compound. Decomposition (D) involves a single compound breaking down into simpler substances. Double replacement is the only option where two ionic compounds exchange partners, making it the correct choice in this scenario.

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.