Among the processes you mentioned, isothermal compression is the reversible process.
Isothermal compression refers to a compression process that occurs at constant temperature. In this process, the system's volume is reduced while the temperature remains constant, resulting in a decrease in pressure. It is considered reversible because it can be reversed by applying the same external pressure to the system while maintaining the temperature constant, leading to an expansion and the system returning to its original state.
On the other hand, the transfer of heat by conduction and radiation, as well as electrical heating of a nichrome wire, are all irreversible processes.
Heat transfer by conduction involves the transfer of thermal energy between objects or within a material due to temperature differences. It occurs through molecular collisions and diffusion of energy. Conduction is generally an irreversible process because it is driven by temperature gradients and naturally moves from regions of higher temperature to lower temperature, without spontaneously reversing.
Heat transfer by radiation involves the emission and absorption of electromagnetic waves (radiation) due to temperature differences between objects. While radiation itself is reversible, the net transfer of heat between objects by radiation is generally an irreversible process, as it is influenced by factors like temperature, emissivity, and geometry.
Electrical heating of a nichrome wire occurs when an electric current passes through the wire, causing it to heat up due to the wire's resistance. This process is irreversible because the conversion of electrical energy into heat is a one-way process, and it is difficult to reverse the heat transfer generated by the electrical current flowing through the wire.
So, among the mentioned processes, only isothermal compression is reversible.