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1. 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.

2. Which element has an atomic mass greater than that of sodium?

• A. Boron
• B. Oxygen
• C. Fluorine
• D. Silicon

Correct answer: D

Rationale: Silicon has an atomic mass greater than that of sodium. The atomic mass of silicon is approximately 28.0855 u, whereas the atomic mass of sodium is approximately 22.9898 u. Therefore, silicon has a greater atomic mass compared to sodium. Boron, Oxygen, and Fluorine have atomic masses lower than sodium, making them incorrect choices in this context.

3. What is 0 K equal to in °C?

• A. -300°C
• B. -273°C
• C. -250°C
• D. -200°C

Correct answer: B

Rationale: 0 Kelvin, also known as absolute zero, is equal to -273°C. This is the point at which all molecular motion stops, making it the lowest possible temperature on the Kelvin scale. Choice A (-300°C) is incorrect as it is not the correct conversion of 0 K to °C. Choice C (-250°C) and Choice D (-200°C) are also incorrect as they do not correspond to the accurate conversion of 0 K to °C.

4. What type of reaction involves atoms attempting to achieve stable electron configurations?

• A. Chemical
• B. Nuclear
• C. Physical
• D. Mechanical

Correct answer: A

Rationale: In a chemical reaction, atoms interact to achieve stable electron configurations through the formation of new chemical bonds or the breaking of existing ones. This process aims to reach a more stable state by filling or emptying electron orbitals, leading to the formation of new substances with more stable configurations. Choice B, nuclear reactions, involve changes in the atomic nucleus rather than electron configurations. Choice C, physical reactions, involve changes in physical state or appearance without changing the chemical makeup. Choice D, mechanical reactions, do not involve the rearrangement of electrons to achieve stable configurations.

5. Which best defines the molarity of an aqueous sugar solution?

• A. Grams of sugar per milliliter of solution
• B. Moles of sugar per milliliter of solution
• C. Grams of sugar per liter of solution
• D. Moles of sugar per liter of solution

Correct answer: D

Rationale: The molarity of a solution is defined as the number of moles of solute per liter of solvent. In the case of an aqueous sugar solution, the molarity would be expressed as moles of sugar per liter of solution. This is because molarity is a measurement of the concentration of a solute in a solution based on the number of moles present in a given volume of the solution. Therefore, the correct answer is D. Choices A, B, and C are incorrect because the molarity is specifically defined in terms of moles of solute per liter of solution, not in grams per milliliter or grams per liter. Molarity is a unit of concentration that relates the amount of solute to the volume of the solution, not the mass of the solute.

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