Chemistry HESI A2 Quizlet

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.

Correct Answer: C

Rationale: The correct answer is C: Electronegativity. Polarity in a molecule is determined by the difference in electronegativity between atoms forming a bond. The greater the electronegativity difference, the more polar the bond and molecule. This is because electronegativity measures an atom's ability to attract electrons towards itself. Bond length (A) and bond strength (B) do not directly determine polarity, although shorter and stronger bonds can influence polarity indirectly. Molecular weight (D) is not a factor in determining polarity, as it relates to the total mass of a molecule rather than its polarity.

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.

Correct Answer: A

Rationale: The Group VIIA elements, also known as the halogens, have a charge of -1. This is because they require one additional electron to achieve a stable octet configuration, making them highly reactive nonmetals. The correct answer is A (-1) because halogens readily gain one electron to fill their outer energy level. Choices B (-2) and D (1) are incorrect because the charge of Group VIIA elements is typically -1, not -2 or +1. Choice C (0) is incorrect because Group VIIA elements do not have a charge of 0; they have a tendency to gain an electron rather than lose one.

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.