Question

The change in internal energy of a system depends upon

• A. initial and final states of a system
• B. path followed by system
• C. total energy of final state only
• D. number of steps involved in system

Hint:

Work ($W$) and heat ($q$) are path functions and depend on how a process is done. Internal energy ($U$), enthalpy ($H$), entropy ($S$), and Gibbs free energy ($G$) are state functions and only care about the start and finish lines.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
We need to identify the thermodynamic defining factor that determines the change in internal energy ($\Delta U$) of a system.

Step 2: Detailed Explanation:
In chemical thermodynamics, physical properties are classified as either state functions or path functions.
Internal energy ($U$) represents the total kinetic and potential energy of all particles inside a system. It is a fundamental state function.
A state function's value is completely determined by the present condition (state) of the system, defined by variables like pressure, volume, and temperature.
Because it is a state function, the overall change in internal energy ($\Delta U$) depends purely on the difference between the final state and the initial state ($\Delta U = U_{final} - U_{initial}$).
It is completely independent of the route, mechanism, or number of steps taken to achieve that state.

Step 3: Final Answer:
The change depends upon the initial and final states of a system, matching option (A).