Nursing Elites

1. Which of the following substances can donate a hydroxide ion (OH-) in solution?

• A. Salt
• B. Base
• C. Neutral compound
• D. Dehydrating agent

Correct answer: B

Rationale: The correct answer is B: Base. A base is a substance that can donate hydroxide ions (OH-) in solution. Bases increase the concentration of hydroxide ions by either accepting protons (H+) or donating hydroxide ions. Salts are ionic compounds made of cations and anions, which do not directly donate hydroxide ions. Neutral compounds do not significantly affect the concentration of hydroxide ions. Dehydrating agents are substances that remove water molecules from other compounds, unrelated to donating hydroxide ions.

2. What element is responsible for the green color of leaves?

• A. Magnesium
• B. Iron
• C. Copper
• D. Zinc

Correct answer: A

Rationale: Magnesium is the correct answer. It is essential for the formation of chlorophyll, the green pigment in plants that is crucial for photosynthesis. Chlorophyll absorbs sunlight and uses its energy to convert carbon dioxide and water into glucose and oxygen. Iron, copper, and zinc do not play a direct role in the green color of leaves. Iron is more related to processes like electron transport, copper is involved in enzyme functions, and zinc contributes to the synthesis of plant growth regulators.

3. What is the main function of estuaries?

• A. Filtering pollutants from water
• B. Providing habitat for marine life
• C. Storing carbon dioxide
• D. Generating wind power

Correct answer: B

Rationale: Estuaries are coastal areas where freshwater from rivers and streams mixes with saltwater from the ocean. They serve as important habitats for a variety of marine life, including fish, birds, and other wildlife. Estuaries provide shelter, breeding grounds, and food sources for many species, making them crucial for the overall health of marine ecosystems. While estuaries can help filter pollutants to some extent, their primary function is to support and sustain diverse populations of plants and animals. Storing carbon dioxide and generating wind power are not main functions of estuaries.

4. 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.

5. What describes the change in direction of light when it passes through different mediums, such as air and water?

• A. Diffraction
• B. Reflection
• C. Refraction
• D. Dispersion

Correct answer: C

Rationale: Refraction is the change in direction of light as it moves from one medium to another, such as air to water or glass. This change occurs due to variations in the speed of light in each medium, causing the light rays to bend. When light passes through different mediums, it changes its path, a phenomenon known as refraction. Choice A, Diffraction, refers to the bending of waves around obstacles and the spreading of waves when passing through small openings, not the change in direction of light when moving between mediums. Choice B, Reflection, is the bouncing back of light rays from a surface into the same medium, not the change in direction when transitioning between different mediums. Choice D, Dispersion, involves the separation of light into its constituent colors based on their different wavelengths, not the change in direction of light when passing through different mediums.

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