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 sum of protons and neutrons in an element represents the mass number. Protons and neutrons are located in the nucleus and contribute to the mass of an atom. The atomic number (A) is the number of protons in an atom, not the sum of protons and neutrons. Atomic mass (C) is the average mass of an element's isotopes, considering their abundance, and is not the sum of protons and neutrons. Neutron number (D) refers to the specific number of neutrons in an atom, not the total mass of the nucleus. Therefore, the correct answer is B, as it accurately represents the total mass of an atom.

Correct Answer: A

Rationale: The correct answer is A: Enzyme. Enzymes can act as catalysts in chemical reactions by lowering the activation energy required for the reaction to occur, thereby speeding up the reaction without being consumed in the process. Enzymes are biological molecules that are highly specific to their substrates and can facilitate a wide range of chemical reactions. Explanation for why the other choices are incorrect: B: Light - Light can initiate certain chemical reactions by providing energy, but it is not a catalyst as it is not directly involved in lowering the activation energy. C: Water - Water can be a solvent or participate in chemical reactions, but it does not act as a catalyst by lowering activation energy. D: Metal - Some metals can act as catalysts in certain reactions, but not all metals have catalytic properties, and they do not have the same specificity and efficiency as enzymes in biological systems.

Correct Answer: B

Rationale: The correct answer is B: Double replacement. In this type of reaction, two ionic compounds swap ions to form two new compounds. The cations and anions switch partners, leading to the formation of two different ionic compounds. This process is also known as metathesis. Single replacement (A) involves an element replacing another in a compound. Synthesis (C) involves the combination of two or more substances to form a single compound. Decomposition (D) involves a single compound breaking down into simpler substances. Double replacement is the only option where two ionic compounds exchange partners, making it the correct choice in this scenario.

Correct Answer: C

Rationale: The correct answer is C: Ionic. In an ionic bond, electrons are transferred from one atom to another, resulting in the formation of positively and negatively charged ions that are attracted to each other due to electrostatic forces. This bond is formed between a metal and a non-metal. Covalent bonds (choice A) involve the sharing of electrons between atoms, not the transfer. Metallic bonds (choice B) occur between metal atoms sharing a sea of electrons. Hydrogen bonds (choice D) are weak attractions between a hydrogen atom and a highly electronegative atom.