Nursing Elites

1. How many mL of a 0 M stock solution of HCl should be added to water to create 250 mL of a 50 M solution of HCl?

• A. 31.25 mL
• B. 32 mL
• C. 30 mL
• D. 31.3 mL

Correct answer: B

Rationale: To prepare 250 mL of a 50 M solution of HCl, the formula V1 x C1 = V2 x C2 is used, where V1 is the volume of the stock solution, C1 is the concentration of the stock solution, V2 is the final volume of the desired solution, and C2 is the final concentration of the desired solution. Given V1 x 0 M = 250 mL x 50 M, solving for V1 results in V1 = (250 mL x 50 M) / 0 M = 32 mL. Therefore, 32 mL of the 0 M stock solution of HCl needs to be added to water to create a 250 mL solution of 50 M HCl. Choices A, C, and D are incorrect because they do not represent the accurate volume required for the dilution calculation based on the given concentrations and volumes in the problem.

2. Most catalysts found in biological systems are which of the following?

• A. Special lipids called cofactors.
• B. Special proteins called enzymes.
• C. Special lipids called enzymes.
• D. Special proteins called cofactors.

Correct answer: B

Rationale: Enzymes are special proteins that act as catalysts in biological systems. They accelerate chemical reactions by lowering the activation energy required for the reaction to occur. Enzymes play a critical role in the regulation of metabolic pathways and are essential for various biological processes. While some enzymes may require cofactors for activity, the enzymes themselves are the catalysts in biological systems. Therefore, choice B, special proteins called enzymes, is the most suitable answer. Choices A, C, and D are incorrect because enzymes, not lipids, are the primary catalysts in biological systems.

3. What is the atomic number of an element?

• A. The number of protons in an atom's nucleus.
• B. The number of neutrons in an atom's nucleus.
• C. The number of electrons in an atom's valence shell.
• D. The number of isotopes of an element.

Correct answer: A

Rationale: The atomic number of an element is the number of protons in an atom's nucleus. This number is crucial as it determines the element's identity and its position on the periodic table. Option B is incorrect because the number of neutrons can vary in isotopes but is not the atomic number. Option C is incorrect as the number of electrons in an atom's valence shell can vary based on the element's charge, not defining the atomic number. Option D is also incorrect because the number of isotopes is not the atomic number of an element.

4. What is the term for the ability of a substance to dissolve in another substance?

• A. Solubility
• B. Miscibility
• C. Immiscibility
• D. Reactivity

Correct answer: A

Rationale: Solubility is the property that describes the ability of a substance to dissolve in another substance. When a substance is soluble in another, it means it can form a homogeneous solution by dispersing at a molecular level within the solvent. Miscibility, on the other hand, refers to the ability of two liquids to mix and form a homogeneous solution. Immiscibility indicates the inability of substances to mix to form a homogeneous solution. Reactivity pertains to the ability of a substance to undergo chemical reactions, which is distinct from the concept of solubility.

5. Which structure in the eye is responsible for detecting light?

• A. Cornea
• B. Retina
• C. Lens
• D. Iris

Correct answer: B

Rationale: The retina is the correct answer as it is the light-sensitive structure in the eye that detects light and converts it into signals for the brain to process visual information. The cornea is the transparent outer covering of the eye that helps to focus incoming light onto the lens. The lens further focuses the light onto the retina, which is where the actual light detection and signal conversion occur. The iris, on the other hand, controls the amount of light entering the eye by adjusting the size of the pupil but is not directly responsible for detecting light.

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