When did diesel locomotives replace steam locomotives?

Which of the following statements are true for an isothermal process? check all that apply. - during an isothermal process, the work done by the gas equals the heat added to the gas. - during an isothermal process, the internal energy of the system changes. - an isothermal process is carried out at constant temperature. - an isothermal process is carried out at constant pressure. - an isothermal process is carried out at constant volume.