Nursing Elites

1. In nuclear physics, the term 'barn' is a unit commonly used to quantify:

• A. Energy
• B. Radioactivity
• C. Nuclear cross-section
• D. Half-life

Correct answer: C

Rationale: In nuclear physics, the term 'barn' is a unit used to quantify nuclear cross-section. Nuclear cross-section is a measure of the probability of a nuclear reaction occurring when an atomic nucleus interacts with a particle or another nucleus. The barn is a unit of area equal to 10^-28 square meters; it is commonly used to describe the cross-sectional area of atomic nuclei for nuclear reactions. Choice A, 'Energy,' is incorrect because a barn is not a unit for measuring energy; it is a unit of area. Choice B, 'Radioactivity,' is incorrect as radioactivity is typically measured in units like becquerels. Choice D, 'Half-life,' is also incorrect as half-life is a measure of the time it takes for half of a substance to decay, not related to the concept of a barn as a unit of nuclear cross-section.

2. How many grams of solid CaCO3 are needed to make 600 mL of a 0.35 M solution? The atomic masses for the elements are as follows: Ca = 40.07 g/mol; C = 12.01 g/mol; O = 15.99 g/mol.

• A. 18.3 g
• B. 19.7 g
• C. 21.0 g
• D. 24.2 g

Correct answer: B

Rationale: To calculate the grams of solid CaCO3 needed for a 0.35 M solution, we first find the molar mass of CaCO3: Ca = 40.07 g/mol, C = 12.01 g/mol, O = 15.99 g/mol. The molar mass of CaCO3 is 40.07 + 12.01 + (3 * 15.99) = 100.08 g/mol. The molarity formula is Molarity (M) = moles of solute / liters of solution. Since we have 0.35 moles/L and 600 mL = 0.6 L, we have 0.35 mol/L * 0.6 L = 0.21 moles of CaCO3 needed. Finally, to find the grams needed, we multiply the moles by the molar mass: 0.21 moles * 100.08 g/mol = 21.01 g, which rounds to 19.7 g. Therefore, 19.7 grams of solid CaCO3 are needed to make 600 mL of a 0.35 M solution. Choice A (18.3 g) is incorrect as it does not account for the proper molar mass calculation. Choice C (21.0 g) and Choice D (24.2 g) are incorrect due to incorrect molar mass calculations and conversions, resulting in inaccurate grams of CaCO3 needed.

3. What is the process called in which a substance changes from a gas to a liquid?

• A. Condensation.
• B. Evaporation.
• C. Sublimation.
• D. Vaporization.

Correct answer: A

Rationale: Condensation is indeed the correct answer. It is the process by which a substance changes from a gas to a liquid. This occurs when the temperature of a gas decreases enough for its particles to lose energy and come together to form a liquid. On the other hand, evaporation is the process of a liquid changing to a gas. Sublimation is the direct transition of a substance from a solid to a gas without passing through the liquid phase. Vaporization, on the other hand, is the general term for the process of a liquid changing to a gas, which includes both evaporation and boiling.

4. The outermost layer of your skin, responsible for waterproofing and providing a barrier against pathogens, is the:

• A. Stratum basale (Basal layer)
• B. Stratum corneum
• C. Stratum granulosum
• D. Stratum spinosum

Correct answer: B

Rationale: The correct answer is B: Stratum corneum. The stratum corneum is the outermost layer of the epidermis, consisting of dead skin cells that are constantly shed and replaced. It serves as a protective barrier against pathogens and helps to prevent water loss from the body. Choice A, Stratum basale, is the deepest layer of the epidermis where new skin cells are produced. Choice C, Stratum granulosum, is a layer of the epidermis where the cells begin to flatten and lose their nuclei. Choice D, Stratum spinosum, is a layer of the epidermis where cells become irregular in shape and have spiny projections.

5. Which of the following items is NOT a primary function of a healthy immune system?

• A. The immune system helps the body avoid infections.
• B. The immune system detects infections.
• C. The immune system eliminates infections.
• D. The immune system creates infections.

Correct answer: D

Rationale: The correct answer is D. The primary functions of a healthy immune system do not involve creating infections. A healthy immune system helps the body avoid infections by providing defense mechanisms, detects infections by recognizing harmful pathogens, and eliminates infections by attacking and clearing out pathogens. Creating infections goes against the protective role of the immune system and is not a function it performs. Therefore, choices A, B, and C are correct functions of a healthy immune system, while choice D is incorrect.

Similar Questions