Nursing Elites

1. Which term describes a substance's ability to undergo a change that transforms it into a different substance?

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

Correct answer: C

Rationale: Reactivity refers to a substance's ability to undergo a change that transforms it into a different substance through a chemical reaction. In this context, reactivity specifically refers to the chemical behavior of a substance. Density, mass, and volume are physical properties of a substance and do not describe its ability to undergo a chemical change. Density is the mass per unit volume, mass is the amount of matter in an object, and volume is the amount of space occupied by an object. Therefore, reactivity is the most appropriate term to describe a substance's ability to undergo a transformation into a different substance.

2. In the electron cloud model, electrons occupy specific energy levels around the nucleus with varying probabilities. This model depicts electrons existing in distinct energy levels, not fixed orbits, with probabilities of finding them in specific regions.

• A. 2 protons and 6 neutrons
• B. 2 filled s orbitals and 6 filled p orbitals
• C. 2s orbitals with 2 and 6 electrons, respectively
• D. 4 filled electron shells

Correct answer: C

Rationale: The electron cloud model describes electrons existing in distinct energy levels, not fixed orbits. Option C correctly describes the electron configuration of an atom with 2s orbitals containing 2 electrons and 6 electrons in the 2p orbitals. This configuration aligns with the electron cloud model where electrons are found in specific energy levels with varying probabilities. Options A, B, and D do not accurately represent the electron cloud model.

3. What is the approximate composition of blood?

• A. 45% plasma, 55% formed elements
• B. 55% plasma, 45% formed elements
• C. 55% water, 45% blood cells
• D. 45% water, 55% plasma

Correct answer: B

Rationale: Blood is composed of approximately 55% plasma (mostly water with proteins, electrolytes, and nutrients) and 45% formed elements (red blood cells, white blood cells, and platelets). Choice B is the correct answer. Choice A is incorrect as it reverses the percentages. Choice C is incorrect because it incorrectly states that blood cells make up 45% of blood, while they are part of the formed elements along with platelets. Choice D is incorrect as it suggests that water makes up 45% of blood, which is not accurate.

4. What phenomenon explains the bending of light as it passes around an obstacle or through an aperture?

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

Correct answer: C

Rationale: Diffraction is the phenomenon that explains the bending of light as it passes around an obstacle or through an aperture. When light encounters an obstacle or passes through an aperture, it diffracts, causing it to bend around the edges. Refraction, on the other hand, occurs when light passes from one medium to another, causing it to change direction. Reflection involves the bouncing back of light rays from a surface, and dispersion is the separation of light into its different colors. Therefore, the correct answer is C, as diffraction specifically addresses the bending of light as it interacts with obstacles or apertures, unlike the other choices that describe different optical phenomena.

5. When magnesium metal reacts with hydrochloric acid, hydrogen gas is produced. What evidence suggests a chemical reaction is occurring?

• A. A change in color
• B. The formation of a gas
• C. Dissolving in a liquid
• D. No change in temperature

Correct answer: B

Rationale: The formation of a gas is evidence of a chemical reaction occurring. In this case, when magnesium metal reacts with hydrochloric acid, hydrogen gas is produced, indicating a chemical change is taking place. The production of gas is a clear indication of a chemical reaction, as new substances are being formed. A change in color might suggest a physical change, dissolving in a liquid could be a physical or chemical change depending on the context, and no change in temperature does not necessarily indicate a chemical reaction, as some reactions are endothermic or release small amounts of heat that may not be easily noticeable.

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