Chemistry HESI A2 Quizlet

Correct Answer: A

Rationale: The correct answer is A: Decomposition. This reaction involves breaking down a compound into simpler components through the use of heat, light, or electricity. Decomposition reactions are the opposite of synthesis reactions, where compounds are formed from simpler substances. Combustion involves the reaction of a substance with oxygen to produce heat and light. Single replacement reactions occur when one element replaces another in a compound. In this context, only decomposition aligns with the process of breaking down a compound into its component parts.

Correct Answer: A

Rationale: The correct answer is A: Unequal sharing of electrons. In a covalent bond, when two different atoms with different electronegativities come together, one atom attracts the shared electrons more strongly than the other, leading to an uneven distribution of electron density. This results in a dipole moment where one end of the bond is slightly positive and the other slightly negative. Choices B, C, and D are incorrect because in covalent bonds, electrons are not fully transferred or exchanged, but rather shared between atoms, leading to the creation of a dipole due to the unequal sharing of 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: B

Rationale: Stoichiometry is the study of mass relationships in chemical reactions. It involves calculating the quantities of reactants and products. By using balanced chemical equations, one can determine the amounts of substances involved. This answer is correct because it directly relates to the main concept of stoichiometry. Explanation for other choices: A: The study of energy changes in chemical reactions - This is incorrect as it refers to the field of thermodynamics. C: The study of atomic structure - This is incorrect as it pertains to atomic theory and not the mass relationships in reactions. D: The study of molecular geometry - This is incorrect as it deals with the spatial arrangement of atoms in molecules, not the mass relationships in reactions.

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.