Chemistry HESI A2 Quizlet

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: 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: 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: 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: 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.