Chemistry HESI A2 Quizlet

Chemistry HESI A2 Quizlet Related

Review Chemistry HESI A2 Quizlet related questions and content

Which law states that matter can neither be created nor destroyed during a chemical reaction?

  • A. Law of Conservation of Energy
  • B. Law of Conservation of Mass
  • C. Law of Constant Composition
  • D. Law of Multiple Proportions
Correct Answer: B

Rationale: The correct answer is B, the Law of Conservation of Mass. This law, formulated by Antoine Lavoisier, states that matter cannot be created or destroyed in a chemical reaction. It is a fundamental principle in chemistry that explains the preservation of mass during chemical reactions, indicating that the total mass of the reactants is equal to the total mass of the products. The other choices are incorrect because:
A: The Law of Conservation of Energy states that energy cannot be created or destroyed, not matter.
C: The Law of Constant Composition refers to compounds having the same composition by mass regardless of their source or how they were prepared, not about the conservation of matter in reactions.
D: The Law of Multiple Proportions describes the ratios in which elements combine to form compounds, not the conservation of mass.

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What is the chemical reaction that involves breaking down a compound into component parts?

  • A. Decomposition
  • B. Synthesis
  • C. Combustion
  • D. Single replacement
Correct Answer: A

Rationale: Decomposition is the correct answer because in a decomposition reaction, a compound is broken down into simpler substances. This type of reaction involves the splitting of a compound into its component parts, often through the use of heat, light, or electricity. Synthesis (choice B) is the opposite process where simpler substances are combined to form a more complex compound. Combustion (choice C) is a reaction involving rapid oxidation often accompanied by heat and light. Single replacement (choice D) is a reaction where one element replaces another in a compound.

How many electron pairs are shared to form a triple covalent bond?

  • A. 1
  • B. 2
  • C. 3
  • D. 4
Correct Answer: C

Rationale: The correct answer is C. In a triple covalent bond, three pairs of electrons are shared between two atoms. This sharing results in a total of six electrons being shared, making the bond strong. Choice A (1) is incorrect because a single covalent bond involves the sharing of one pair of electrons. Choice B (2) is incorrect as a double covalent bond consists of the sharing of two pairs of electrons. Choice D (4) is incorrect because there are only three pairs of electrons shared in a triple covalent bond, not four.

What is the simplest form of a substance that is represented by a letter or letters?

  • A. Compound
  • B. Mixture
  • C. Element
  • D. Molecule
Correct Answer: C

Rationale: The correct answer is C, 'Element.' An element is the most basic form of a substance that cannot be broken down further by chemical reactions. Each element is represented by a unique symbol, typically consisting of one or two letters. Choice A, 'Compound,' is incorrect as compounds are formed by the combination of two or more elements. Choice B, 'Mixture,' is also incorrect as mixtures are composed of two or more substances physically combined. Choice D, 'Molecule,' refers to the smallest unit of a compound that retains the chemical properties of that compound, not the simplest form of a substance represented by a symbol.

What can stop the penetration of alpha particles?

  • A. Aluminum foil
  • B. Glass
  • C. Piece of paper
  • D. Plastic
Correct Answer: C

Rationale: Alpha particles can be stopped by a piece of paper due to their low penetration power. The paper acts as a shield, effectively blocking the alpha particles from passing through. In contrast, materials like aluminum foil, glass, and plastic are not as effective as a simple piece of paper in stopping alpha particles. Aluminum foil is more effective against beta particles, gamma rays, and x-rays due to its higher density. Glass and plastic also provide some protection against beta particles and gamma rays, but they are less effective than a piece of paper against alpha particles.

Which type of chemical reaction involves two ionic compounds where the reactants yield 'switched partners'?

  • A. Single replacement
  • B. Double replacement
  • C. Synthesis
  • D. Decomposition
Correct Answer: B

Rationale: The correct answer is 'Double replacement.' In a double replacement reaction, two ionic compounds react by exchanging ions, resulting in the formation of two new compounds where the positive and negative ions have 'switched partners.' This type of reaction is characterized by the exchange of ions between the reactants. Choice A, 'Single replacement,' involves an element replacing another in a compound, not the exchange of partners like in the given scenario. Choice C, 'Synthesis,' is the combination of two or more substances to form a more complex product, not involving the exchange of partners. Choice D, 'Decomposition,' is the breakdown of a compound into simpler substances, which is different from the scenario described in the question.

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