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: Read what is asked.
We must find what the change in internal energy $\Delta U$ of a system depends on.

Step 2: Know what internal energy is.
Internal energy is the total energy stored inside the system, in the motion and position of its particles.

Step 3: Learn the idea of a state function.
A state function depends only on the present condition of the system, such as its pressure, volume, and temperature.

Step 4: Place internal energy.
Internal energy is a state function. So its change depends only on where the system starts and where it ends.

Step 5: Write the rule.
\[ \Delta U = U_{final} - U_{initial} \] The path taken, or the number of steps, does not matter.

Step 6: Conclusion.
So $\Delta U$ depends only on the initial and final states. Heat and work do depend on the path, but internal energy does not. \[ \boxed{\text{Initial and final states (Option 1)}} \]