Nursing Elites

1. Identify the type of reaction shown: 8Fe + S → 8FeS

• A. Single displacement
• B. Double displacement
• C. Synthesis
• D. Acid-base

Correct answer: C

Rationale: The reaction shown (8Fe + S → 8FeS) is a synthesis reaction. In a synthesis reaction, two or more substances combine to form a single compound. In this case, iron (Fe) and sulfur (S) combine to form iron sulfide (FeS). The key characteristic of a synthesis reaction is the formation of a single product from multiple reactants, which aligns with the given chemical equation. Choice A, single displacement, involves an element displacing another in a compound, which is not the case here. Choice B, double displacement, involves the exchange of ions between two compounds, which is also not happening in this reaction. Choice D, acid-base, refers to reactions between an acid and a base to form salt and water, which is not the case in the given equation.

2. What is stoichiometry?

• A. The study of energy changes in chemical reactions
• B. The study of the mass relationships in chemical reactions
• C. The study of atomic structure
• D. The study of molecular geometry

Correct answer: B

Rationale: Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions. It focuses on the calculation of the amounts of substances consumed and produced in a reaction based on the balanced chemical equation. Choice A is incorrect because the study of energy changes in chemical reactions falls under thermodynamics. Choice C is incorrect as atomic structure is related to the arrangement of atoms within molecules. Choice D is incorrect as molecular geometry deals with the spatial arrangement of atoms within molecules.

3. The three important allotropic forms of phosphorus are red, white, and ___________.

• A. green
• B. gray
• C. black
• D. silver

Correct answer: C

Rationale: The three important allotropic forms of phosphorus are red, white, and black. These forms indicate the different physical properties and reactivity of phosphorus under various conditions. Red phosphorus is more stable and less reactive than white phosphorus, while black phosphorus is the least reactive form. Choice C, 'black,' is the correct answer as it completes the sequence of allotropic forms of phosphorus. Choices A, 'green,' B, 'gray,' and D, 'silver,' are incorrect as they do not represent recognized forms of phosphorus.

4. Which factor does not affect the reaction rate of a chemical reaction?

• A. Temperature
• B. Surface area
• C. Concentration of reactants
• D. Color of the reactants

Correct answer: D

Rationale: The color of reactants is not a factor that affects the rate of a chemical reaction. Temperature, surface area, and concentration of reactants are known factors that influence the reaction rate. Temperature plays a significant role in altering the reaction rate by affecting the kinetic energy of molecules. Surface area impacts the rate by providing more area for collisions to occur. Concentration affects the frequency of effective collisions. On the other hand, the color of reactants is a physical property that does not directly affect the speed of a chemical reaction.

5. You contain two odorous gases in vials with porous plugs. Gas A has twice the mass of Gas B. Which observation is most likely?

• A. You will smell Gas A before you smell Gas B.
• B. You will smell Gas B before you smell Gas A.
• C. You will smell Gas A but not Gas B.
• D. You will smell Gas B but not Gas A.

Correct answer: A

Rationale: The rate of effusion of a gas is inversely proportional to the square root of its molar mass. Since Gas A has twice the mass of Gas B, Gas A will effuse more slowly than Gas B. Therefore, you will likely smell Gas A before you smell Gas B as Gas A will escape and diffuse through the porous plug at a slower rate compared to Gas B. Choice A is correct because Gas A, with its higher molar mass, will take longer to effuse through the porous plug, causing you to smell it first. Choices B, C, and D are incorrect as they do not consider the relationship between molar mass and effusion rate.

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