Final answer:
In an isothermal process, the final temperature of a system or substance remains unchanged from the initial temperature. Therefore, if a gas starts at 30°C and undergoes an isothermal process, the final temperature will also be 30°C.
Step-by-step explanation:
If the process involving a substance or system is isothermal, it means that the temperature remains constant throughout the process. According to the first law of thermodynamics for an isothermal process in an ideal gas, the change in internal energy (ΔEint) is zero, hence the heat added to the system (Q) is equal to the work done by the system (W). Consequently, if you start with an ideal gas at a certain temperature and it undergoes an isothermal expansion or compression, the final temperature of the gas will remain the same as the initial temperature.
In the scenarios provided in your homework questions, even though they mention processes like isochoric and adiabatic, when the situation is specifically isothermal, the final temperature must be the same as the initial temperature. For instance, starting with a gas at 30°C and having it undergo an isothermal process means the final temperature would also be 30°C. All the other calculations for changes in entropy, work, or internal energy would have to take into account that the temperature does not change in the isothermal case.