Chemistry HESI A2 Quizlet

Correct Answer: A

Rationale: The correct answer is A: Polar. In a covalent bond, if electrons are not shared equally, the bond is considered polar. This occurs when one atom has a higher electronegativity than the other, leading to an uneven distribution of electron density. As a result, one end of the bond will have a partial negative charge while the other end will have a partial positive charge, creating a dipole moment. Choices B (Non-polar) and D (Hydrogen) are incorrect because they do not specifically address the unequal sharing of electrons in a covalent bond. Choice C (Ionic) is incorrect as ionic bonds involve the complete transfer of electrons, not sharing.

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.

Correct Answer: B

Rationale: Increasing the concentration of reactants increases the chances of reactant molecules colliding, leading to more successful collisions and higher reaction rate. This is explained by the collision theory in chemistry. Choice A is incorrect because increasing concentration typically increases the reaction rate. Choice C is incorrect as increasing concentration does not stop the reaction, but rather can enhance it. Choice D is also incorrect as concentration of reactants has a direct impact on reaction rate.

Correct Answer: A

Rationale: To increase the reaction rate of a chemical reaction, increasing the temperature is the correct answer. This is because raising the temperature provides reactant molecules with more kinetic energy, leading to more frequent and energetic collisions, which increases the likelihood of successful collisions and hence the reaction rate. Increasing the surface area (choice B) can enhance the reaction rate for solid reactants but is not universally applicable. Increasing the concentration of reactants (choice C) can increase the reaction rate by providing more reactant molecules for collisions, but it may not always be the most effective method compared to temperature. Adding a catalyst (choice D) can lower the activation energy and speed up the reaction rate, but it is not the only way to increase reaction rates.

Correct Answer: B

Rationale: The correct answer is B: By their chemical properties. The periodic table arranges elements based on their atomic number, which determines their chemical properties. Elements in the same column have similar properties due to their shared electron configurations. This organization helps predict an element's behavior in chemical reactions. Choices A, C, and D are incorrect because atomic mass, physical state, and charge do not determine an element's position in the periodic table or its relationship to other elements.