Thermodynamics

JEE Main level, single correct, medium

37 of 190

Question 37 of 190

Given below are two statements. One is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : If
dQdQ and dWdW represent the heat supplied to the system and the work done on the system respectively. Then according to the first law of thermodynamics dQ=dU−dWdQ=dU-dW.
Reason R : First law of thermodynamics is based on law of conservation of energy.

In the light of the above statements, choose the correct answer from the option given below :

Show answer and solution

Answer: (C) Both A and R are correct and R is the correct explanation of A

The first law of thermodynamics is stated as dQ=dU−dWdQ=dU-dW. Since dQdQ is heat supplied to the system and positive thus, dWdW is work done on the system, i.e., negative work.
We know that the first law of thermodynamics deals with work done, and heat energy supplied or removed from a system. Therefore, it is based on the conservation of energy. The law states that energy cannot be created or destroyed; it can only be converted from one form to another.

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