Chemistry HESI A2 Quizlet

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: C

Rationale: Alpha particles are positively charged and relatively large, so they have low penetrating power. A piece of paper can stop alpha particles because the paper's thickness provides enough material for the particles to collide with and lose their energy through ionization. Aluminum foil and glass are not thick enough to effectively stop alpha particles. Plastic, depending on its thickness, may not provide sufficient shielding to stop alpha particles completely. In summary, the correct answer is C because the thickness of a piece of paper is sufficient to stop alpha particles, while the other choices are not adequate for effective shielding.

Correct Answer: C

Rationale: Increasing the surface area of a reactant increases the number of exposed particles available for collision, leading to more frequent and successful collisions. This results in an increased reaction rate. Choice A is incorrect because more surface area facilitates faster reactions. Choice B is incorrect as surface area affects reaction rate. Choice D is incorrect as increasing surface area does not stop the reaction; it actually accelerates it.

Correct Answer: B

Rationale: The correct answer is B: Chemical reaction. In a chemical reaction, bonds are broken and new bonds are formed to create new chemical compounds. The process involves the rearrangement of atoms to form different substances with unique properties. Physical reactions (choice A) involve changes in physical state or appearance without altering the chemical composition. Nuclear reactions (choice C) involve changes in the nucleus of an atom, leading to the formation of different elements. Mechanical reactions (choice D) involve physical forces but do not result in the formation of new chemical compounds.