Chemistry HESI A2 Quizlet

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: Weak. Dipole attraction is a type of intermolecular force where polar molecules are attracted to each other due to the positive and negative ends of their dipoles. This force is relatively weaker compared to other intermolecular forces like hydrogen bonding or ion-dipole interactions. It is weaker because it only involves the partial charges on molecules and not full charges like in ionic interactions. Choices A, C, and D are incorrect because dipole attractions are not as strong as those intermolecular forces that involve full charges or hydrogen bonding.

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: Dispersion forces are the weakest intermolecular forces present in non-polar covalent compounds due to temporary dipoles. Non-polar compounds have symmetrical distribution of electrons, leading to temporary shifts in electron density causing dispersion forces. Polar compounds (choice A) have permanent dipoles, ionic compounds (choice C) have strong electrostatic forces, and hydrogen compounds (choice D) involve hydrogen bonding - all of which are stronger than dispersion forces and not typically found in non-polar compounds. Therefore, the correct answer is B - non-polar covalent compounds.

Correct Answer: B

Rationale: Stoichiometry is the study of mass relationships in chemical reactions. It involves calculating the quantities of reactants and products. By using balanced chemical equations, one can determine the amounts of substances involved. This answer is correct because it directly relates to the main concept of stoichiometry. Explanation for other choices: A: The study of energy changes in chemical reactions - This is incorrect as it refers to the field of thermodynamics. C: The study of atomic structure - This is incorrect as it pertains to atomic theory and not the mass relationships in reactions. D: The study of molecular geometry - This is incorrect as it deals with the spatial arrangement of atoms in molecules, not the mass relationships in reactions.