Chemistry HESI A2 Quizlet

Correct Answer: B

Rationale: The correct answer is B: Gas. Gases change in volume with changes in temperature and pressure according to the ideal gas law (PV = nRT). When temperature or pressure increases, gas molecules move faster and occupy more space, leading to an increase in volume. Liquids (choice A) have relatively fixed volumes, solids (choice C) have definite shapes and volumes, and plasmas (choice D) are ionized gases with unique properties but still do not change volume based on temperature and pressure changes.

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: C

Rationale: The correct answer is C, atomic number. The atomic number represents the number of protons in an element. This is because the atomic number is the unique identifier of an element and determines its chemical properties. Protons are the positively charged particles in the nucleus of an atom, and the number of protons defines the element's identity. Explanation for incorrect choices: A: Atomic mass represents the average mass of all isotopes of an element, not the number of protons. B: Mass number is the sum of protons and neutrons in an atom, not just the number of protons. D: "Proton number" is not a standard term in chemistry, and it does not specifically refer to the number of protons in an element.

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.

Correct Answer: D

Rationale: The correct answer is D because fluorine, oxygen, and nitrogen are typically involved in hydrogen bonding due to their high electronegativity, which allows them to form strong partial charges. This creates a polar covalent bond with hydrogen, leading to hydrogen bonding. Fluorine, chlorine, and oxygen (Choice B) are incorrect as chlorine is not typically involved. Carbon, hydrogen, and oxygen (Choice A) lack the necessary electronegativity for hydrogen bonding. Fluorine, chlorine, and nitrogen (Choice C) also lack the required electronegativity for effective hydrogen bonding. In summary, only elements with high electronegativity like fluorine, oxygen, and nitrogen are typically involved in hydrogen bonding.