An ideal gas is pressed at constant temperature. Its internal energy:
Correct answer: D. Remains the same
- A. Decreases
- B. First increases and then decreases
- C. Increases
- D. Remains the same
Explanation
The correct answer is D: Remains the same. For an ideal gas, internal energy is a function of temperature only (U ∝ T). Since the temperature is constant, the internal energy does not change. Option A is incorrect because a decrease in internal energy would require a decrease in temperature, which is not happening. Option B is incorrect because there is no fluctuation in temperature, hence no fluctuation in internal energy. Option C is incorrect because an increase in internal energy would require an increase in temperature, which is also not happening.In summary, for an ideal gas undergoing a process at constant temperature, the internal energy remains constant because it is directly proportional to temperature, and no temperature change occurs.
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About First Law of Thermodynamics
The first law relates heat supplied, work done and the change in internal energy through energy conservation. Problems use sign conventions and apply the law to isothermal, adiabatic, isobaric and isochoric processes. Internal energy is a state function, while heat and work depend on the path followed.
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