The relation for the 1st law of thermodynamics can be expressed as:
Correct answer: B. ∆Q=∆U+∆W
- A. ∆Q=∆W
- B. ∆Q=∆U+∆W
- C. ∆Q=∆U
- D. ∆Q=∆U/∆W
Explanation
The correct expression for the 1st law of thermodynamics is ∆Q=∆U+∆W, which states that the heat energy added to a system (∆Q) is equal to the change in internal energy (∆U) plus the work done by the system (∆W). Option A omits the internal energy change, making it incorrect. Option C omits the work done by the system, which is also incorrect. Option D incorrectly uses division instead of addition, which does not align with the 1st law.
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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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