Nursing Elites

1. How many moles of water are produced when 0.5 moles of methane (CH4) react with excess oxygen?

• A. 0.5 moles
• B. 1 mole
• C. 2 moles
• D. 3 moles

Correct answer: B

Rationale: The balanced chemical equation for the combustion of methane is: CH4 + 2O2 -> CO2 + 2H2O. This equation shows that 1 mole of methane produces 2 moles of water. Therefore, when 0.5 moles of methane react, they will produce 1 mole of water. The ratio of water to methane is 2:1, meaning that for every mole of methane that reacts, it produces 2 moles of water. Since only 0.5 moles of methane are reacting, the amount of water produced will be half of what would be produced if 1 mole of methane reacted, resulting in 1 mole of water being produced. Choice A is incorrect because it does not consider the stoichiometry of the reaction. Choices C and D are incorrect as they do not align with the balanced chemical equation and the stoichiometric ratios involved in the reaction.

2. When is a solution considered saturated?

• A. More solute cannot be dissolved
• B. The solvent starts to evaporate
• C. The solution becomes cloudy
• D. It reaches a specific temperature

Correct answer: A

Rationale: A solution is considered saturated when it has dissolved the maximum amount of solute that can be dissolved at a given temperature. At this point, adding more solute will not result in further dissolution, indicating that the solution is saturated. The other choices are incorrect because the solvent evaporating or the solution becoming cloudy are not definitive indicators of a saturated solution. Additionally, reaching a specific temperature does not determine saturation, as the solubility of a solute can vary with temperature. Therefore, the correct answer is that more solute cannot be dissolved in a saturated solution.

3. What does the term 'dilution' refer to in a solution?

• A. Adding more solvent to decrease concentration
• B. Adding more solute to increase concentration
• C. Reducing the temperature to increase solubility
• D. Increasing pressure to increase solubility

Correct answer: A

Rationale: The term 'dilution' in a solution refers to adding more solvent to decrease the concentration of the solution. Dilution involves reducing the concentration of the solute in the solution by increasing the amount of solvent. Choice B is incorrect because adding more solute would increase the concentration, not decrease it. Choices C and D are also incorrect as they relate to factors affecting solubility, not dilution specifically. Therefore, choice A is the correct answer as it accurately defines the process of dilution in a solution.

4. Which of the following colligative properties refers to the elevation of the boiling point of a solution?

• A. Freezing point depression
• B. Vapor pressure lowering
• C. Osmotic pressure
• D. Boiling point elevation

Correct answer: D

Rationale: The correct answer is D, 'Boiling point elevation.' Boiling point elevation is a colligative property that describes the increase in the boiling point of a solvent when a non-volatile solute is added to it. This occurs because the presence of solute particles in the solvent lowers the vapor pressure of the solution, requiring a higher temperature to reach the same vapor pressure as the pure solvent. Choices A, B, and C are incorrect. Freezing point depression refers to the lowering of the freezing point of a solution, vapor pressure lowering is the reduction in vapor pressure due to the presence of solute particles, and osmotic pressure is the pressure required to prevent the flow of solvent molecules across a semipermeable membrane in osmosis.

5. Which of the following is an example of an aromatic compound?

• A. Ethanol
• B. Toluene
• C. Acetone
• D. Butanal

Correct answer: B

Rationale: Toluene is an aromatic compound due to its benzene ring structure, which satisfies the criteria of aromaticity. Aromatic compounds contain conjugated pi electrons in a ring structure, providing extra stability. Ethanol, acetone, and butanal are not aromatic compounds as they do not possess a benzene ring or meet the aromaticity criteria. Ethanol is an alcohol, acetone is a ketone, and butanal is an aldehyde, none of which have the characteristic benzene ring structure of aromatic compounds.

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