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: 0. Noble gases have a full outer electron shell, making them stable and unreactive. This full shell means they do not gain or lose electrons, so they have no overall charge, making their charge 0. Choice A (-1) is incorrect because it indicates gaining an electron to achieve a full outer shell, which is not characteristic of noble gases. Choices C (1) and D (2) are incorrect as they suggest a positive charge, which noble gases do not possess due to their stable electron configuration.

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: Hydrogen and oxygen. Water decomposes into hydrogen and oxygen through a process called electrolysis. In this process, an electric current is passed through water, causing it to break down into its constituent elements. Hydrogen is produced at the cathode, while oxygen is produced at the anode. This is a well-known and scientifically proven reaction. Choices B, C, and D are incorrect because water does not decompose into carbon dioxide, nitrogen, or methane under normal conditions. This can be confirmed by studying the chemical properties and reactions of water.

Correct Answer: D

Rationale: The correct answer is D: Molar mass. One mole of a substance represents the molar mass, which is the mass of one mole of that substance in grams. This is calculated by summing the atomic masses of all the atoms in the chemical formula. The molar mass is expressed in g/mol and is a fundamental concept in chemistry for performing various calculations. A: Atomic mass refers to the mass of an individual atom of an element, not one mole of a substance. B: Mass number refers to the total number of protons and neutrons in an atom's nucleus, not the mass of one mole of a substance. C: Molecular weight is the sum of the atomic weights of the atoms in a molecule, not the mass of one mole of a substance.