Nursing Elites

1. Which of the following is a common property of bases?

• A. Conductivity in aqueous solutions
• B. Sour taste
• C. Reactivity with metals to produce hydrogen gas
• D. Turns red litmus paper blue

Correct answer: D

Rationale: Bases are substances that can accept protons or donate hydroxide ions in a chemical reaction. One common property of bases is that they turn red litmus paper blue. This is a classic test to distinguish between acids (which turn blue litmus paper red) and bases. Conductivity in aqueous solutions (Option A) is a property of both acids and bases, but not unique to bases alone. Sour taste (Option B) is a property commonly associated with acids, not bases. Reactivity with metals to produce hydrogen gas (Option C) is a property of acids, particularly strong acids, but not bases.

2. What is the term for the mixture of reactants and products present during a chemical reaction?

• A. Solution
• B. Mixture
• C. Reaction mixture
• D. Precipitate

Correct answer: C

Rationale: The term 'reaction mixture' is used to describe the combination of both reactants and products that exist simultaneously during a chemical reaction. It encompasses not only the initial substances (reactants) but also the resulting compounds (products) formed throughout the reaction process. Choice A, 'Solution,' typically refers to a homogenous mixture where one substance is dissolved in another. Choice B, 'Mixture,' is a general term that does not specifically indicate the mix of reactants and products in a chemical reaction. Choice D, 'Precipitate,' specifically refers to the solid formed when two solutions react and a solid compound is produced.

3. How does an increase in temperature generally affect the solubility of most solid solutes in a liquid solvent?

• A. It increases solubility
• B. It decreases solubility
• C. It has no effect on solubility
• D. It depends on the nature of the solute

Correct answer: A

Rationale: In general, increasing temperature tends to increase the solubility of most solid solutes in liquid solvents. This occurs because higher temperatures provide more energy for the solvent molecules to break the solute-solvent attractive forces and allow more solute to dissolve. The increase in temperature facilitates the dissolution process by overcoming the intermolecular forces that hold the solute particles together. Choice B is incorrect because higher temperatures typically lead to greater solubility. Choice C is incorrect as temperature changes usually impact solubility. Choice D is incorrect because although the nature of the solute can influence solubility, the general trend is that higher temperatures enhance solubility for most solid solutes in liquid solvents.

4. Which skin condition is characterized by patches of inflamed, reddened skin and is often triggered by allergens or stress?

• A. Eczema
• B. Psoriasis
• C. Acne
• D. Vitiligo

Correct answer: A

Rationale: Eczema is the correct answer. It presents as patches of inflamed, reddened skin and can be triggered by allergens, stress, or other factors. Psoriasis, on the other hand, is characterized by red, scaly patches rather than inflamed and reddened skin. Acne manifests as pimples and blemishes, not patches of inflamed skin. Vitiligo is characterized by the loss of skin color in patches, which is distinct from the symptoms described in the question.

5. Which cells myelinate neurons in the CNS?

• A. Schwann cells
• B. Astrocytes
• C. Microglia
• D. Oligodendrocytes

Correct answer: D

Rationale: The correct answer is D, Oligodendrocytes. Oligodendrocytes are responsible for myelinating neurons in the central nervous system (CNS). Schwann cells, found in the peripheral nervous system, are responsible for myelinating neurons there. Astrocytes support and maintain the neuronal environment, while microglia function as immune cells in the CNS, participating in immune responses and cellular debris clearance. Therefore, choices A, B, and C are incorrect for myelination of CNS neurons.

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