`5mol` of an ideal gas at `293K` is expanded isothermally from an initial pressure `0.4 kPa` to a final pressure of `0.1kPa` against a constant external pressure of `0.1kPa`.
a. Calcualte `q,w, Delta,U`, and `DeltaH`.
b. Calculate the corresponding value of `q,w, DeltaU`, and `DeltaH` if the above pressure is carried out reversibly.

Explanation

To solve the problem, we will break it down into two parts as specified in the question.

### Part A: Calculate q, w, ΔU, and ΔH for the isothermal expansion against a constant external pressure.

1. **Determine ΔU**:
- For an isothermal process involving an ideal gas, the change in internal energy (ΔU) is given by:
\[
\Delta U = nC_v\Delta T
...