Nursing Elites

1. When the heat of a reaction is negative, which statement is true?

• A. The products have less energy and are less stable.
• B. The products have more energy and are more stable.
• C. The products have less energy and are more stable.
• D. The products have more energy and are less stable.

Correct answer: C

Rationale: When the heat of a reaction is negative, it indicates that the reaction releases energy in the form of heat. This means that the products have lower energy levels compared to the reactants. Lower energy levels are associated with greater stability in chemical systems. Therefore, when the heat of a reaction is negative, the products are more stable due to having less energy than the reactants. Choice A, stating that the products have less energy and are less stable, is incorrect as lower energy levels imply greater stability. Choice B, stating that the products have more energy and are more stable, is incorrect as lower energy levels lead to higher stability. Choice D, stating that the products have more energy and are less stable, is incorrect as lower energy levels are associated with higher stability.

2. A 60-watt lightbulb is powered by a 110-volt power source. What is the current being drawn?

• A. 0.55 amperes
• B. 1.83 amperes
• C. 50 amperes
• D. 6,600 amperes

Correct answer: A

Rationale: To calculate the current being drawn, use the formula I = P / V, where I is the current, P is the power in watts, and V is the voltage. Substituting the given values, I = 60 / 110 ≈ 0.55 amperes. Therefore, the current being drawn by the 60-watt lightbulb is approximately 0.55 amperes. Choice B, 1.83 amperes, is incorrect as it does not match the calculated value. Choices C and D, 50 amperes and 6,600 amperes, are significantly higher values and do not align with the expected current draw of a 60-watt lightbulb powered by a 110-volt source.

3. In open-channel flow, a critical property is the free surface, which refers to the:

• A. Interface between the liquid and the container walls
• B. Interface between the liquid and a surrounding gas
• C. Bottom of the channel
• D. Region of highest velocity within the liquid

Correct answer: B

Rationale: The free surface in open-channel flow refers to the interface between the liquid and the surrounding gas, typically the atmosphere. This interface is critical as it determines the boundary between the liquid flow and the open environment. Option A is incorrect as it refers to the liquid-container wall interface, not the free surface. Option C is incorrect because it represents the bottom of the channel, not the free surface. Option D is incorrect as it describes the region of highest velocity within the liquid, not the free surface. Therefore, the correct choice is B.

4. The specific heat capacity of water is about 2 J/g°C. How much energy would you need to heat 1 kilogram of water by 10°C?

• A. 420 J
• B. 4,200 J
• C. 42,000 J
• D. 420,000 J

Correct answer: C

Rationale: The formula to calculate the energy required to heat a substance is Q = m × c × ΔT, where m is the mass, c is the specific heat capacity, and ΔT is the change in temperature. Given that 1 kilogram of water is equal to 1,000 grams, the mass (m) is 1,000 g, the specific heat capacity (c) of water is 4.2 J/g°C (not 2 J/g°C), and the change in temperature (ΔT) is 10°C. Substituting these values into the formula: Q = 1,000 × 4.2 × 10 = 42,000 J. Therefore, the correct energy required to heat 1 kilogram of water by 10°C is 42,000 J. Choices A, B, and D are incorrect as they do not consider the correct specific heat capacity of water or the conversion of mass to grams.

5. A constant force is exerted on a stationary object. In this scenario, work is:

• A. Performed
• B. Not performed
• C. Partially performed
• D. Inconclusive without further information

Correct answer: B

Rationale: Work is only done when a force causes displacement. Since the object is stationary, no displacement occurs, and therefore, no work is performed. Choice A is incorrect because work requires both force and displacement. Choice C is incorrect as there is no partial work - work is either done or not done. Choice D is incorrect as the scenario provided is clear - the object is stationary, so no work is being performed.

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