Chemistry HESI A2 Quizlet

Correct Answer: B

Rationale: The correct answer is B (-2). Group VIA elements, also known as Chalcogens, have 6 valence electrons. They typically gain 2 electrons to achieve a stable octet configuration, resulting in a -2 charge. Option A (-1) is incorrect because gaining 1 electron would not complete the octet. Option C (-3) is incorrect because gaining 3 electrons is energetically unfavorable. Option D (0) is incorrect because Group VIA elements tend to gain electrons to achieve stability.

Correct Answer: A

Rationale: The correct answer is A: Alpha, beta, gamma. Alpha radiation consists of helium nuclei, beta radiation includes electrons or positrons, and gamma radiation is electromagnetic radiation. This is correct as it covers all three types of radiation commonly encountered in nuclear physics. Choice B is incorrect as delta radiation is not a recognized form of radiation. Choice C is incorrect as delta and epsilon are not types of radiation, and choice D is incorrect as it does not include the correct types of radiation.

Correct Answer: A

Rationale: The correct answer is A because a balanced chemical equation must satisfy the law of conservation of mass. This means that the number of atoms of each element must be the same on both the reactant and product sides. This ensures that no atoms are gained or lost during a chemical reaction. Explanation for why the other choices are incorrect: B: An equation with more products than reactants does not follow the law of conservation of mass. C: Balancing the number of molecules is important, but the key factor is balancing the number of atoms of each element. D: Equal masses on both sides do not necessarily guarantee that the number of atoms of each element is the same.

Correct Answer: C

Rationale: The correct answer is C: Several feet of concrete. Gamma radiation is highly penetrating and requires dense materials to effectively block it. Concrete, being a dense material, can absorb and block gamma radiation effectively due to its high atomic number and thickness. Aluminum foil (A) and glass (B) are not dense enough to stop gamma radiation. Paper (D) is too thin and lacks the density needed to block gamma radiation effectively.

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.