Nursing Elites

1. The Gram stain is a differential staining technique used to classify bacteria based on their cell wall composition. Gram-positive bacteria appear

• A. Pink
• B. Blue
• C. Red
• D. Purple

Correct answer: D

Rationale: The Gram stain is a differential staining technique that categorizes bacteria into two groups based on their cell wall composition: Gram-positive and Gram-negative. Gram-positive bacteria have a thick layer of peptidoglycan in their cell walls, which retains the crystal violet stain used in the Gram staining procedure. Consequently, Gram-positive bacteria appear purple under the microscope after staining. On the other hand, Gram-negative bacteria possess a thinner peptidoglycan layer and an outer membrane that can be penetrated by the counterstain safranin, leading them to appear pink or red. Blue is not typically used to describe the color of bacteria in a Gram stain, making it an incorrect choice.

2. Which of the following is a representation of a natural pattern or occurrence that is difficult or impossible to experience directly?

• A. A theory
• B. A model
• C. A law
• D. An observation

Correct answer: B

Rationale: A model is a representation used by scientists to understand and explain natural phenomena that are challenging or impossible to observe directly. Models help visualize complex systems or processes that are not easily accessible for direct observation. The other choices are incorrect because: A) A theory is an explanation or interpretation of observable facts or phenomena. C) A law describes a consistent and universal phenomenon or relationship in nature based on repeated observations. D) An observation is a direct act of watching or taking note of a phenomenon or behavior.

3. What is the general formula for an alcohol?

• A. CₙH₂ₙ
• B. CₙH₂ₙ₊₂
• C. CₙH₂ₙ₋₁
• D. CₙH₂ₙO

Correct answer: D

Rationale: The correct general formula for an alcohol is CnH2n+1OH, which can be simplified to CnH2nO. In this formula, 'n' represents the number of carbon atoms, '2n' represents the number of hydrogen atoms, and 'O' represents the oxygen atom present in the hydroxyl group of the alcohol. Therefore, the correct general formula for an alcohol is CnH2nO. Choice A, CₙH₂ₙ, does not account for the oxygen atom, which is essential in alcohols. Choice B, CₙH₂ₙ₊₂, does not include the oxygen atom or the necessary hydrogen atoms for the hydroxyl group. Choice C, CₙH₂ₙ₋₁, lacks the oxygen atom and also does not fulfill the requirements of the hydroxyl group. Thus, the most accurate representation of the general formula for an alcohol is CnH2nO.

4. What is the best tool to measure the volume of a solid?

• A. Triple beam balance
• B. Measuring wheel and mathematical formula
• C. Graduated cylinder
• D. Measuring wheel

Correct answer: C

Rationale: A graduated cylinder is the most suitable tool to measure the volume of both liquids and solids. It works by measuring the displacement of water when the solid is submerged in the graduated cylinder. Choice A, the triple beam balance, is used to measure mass, not volume. Choice B, using a measuring wheel and mathematical formula, is typically used to measure distance or area, not volume. Choice D, a measuring wheel, is used to measure distance, making it inappropriate for measuring the volume of a solid.

5. Which property of a substance measures the amount of matter per unit volume?

• A. Density
• B. Mass
• C. Weight
• D. Volume

Correct answer: A

Rationale: Density is the property of a substance that measures the amount of matter per unit volume. It is calculated by dividing the mass of the substance by its volume. Mass refers to the amount of matter in an object, weight is the force of gravity acting on an object, and volume is the amount of space an object occupies. Density specifically quantifies how tightly packed the matter in a substance is, providing a measure of compactness or concentration of matter. Therefore, the correct answer is A, Density.

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