Question

Which of the following statements is correct?

• A. The energy can be created
• B. According to first law of thermodynamics, the energy of an isolated system is not constant
• C. In the isolated system, $W=0,q=0,\Delta U\ne 0$
• D. $\Delta U=q+W$, will depend only on initial and final state

Answer 1

Answer: (D)

Statement (d) is correct, while the other statements are incorrect.
Corrected form are as follows :
$\Delta U=q+W$ is the mathematical expression of the first law of thermodynamics which states that the energy of an isolated system is constant.
i.e. energy can neither be created nor destroyed but can be converted into one form to another.
Moreover, in an isolated system,
$W=0,q=0$ and, therefore $\Delta U=0.$