Explanation:
The equation Q = -w represents the first law of thermodynamics, where Q is the heat absorbed or released by the system and w is the work done by or on the system. However, this equation is not true for adiabatic processes.

Adiabatic Process:
An adiabatic process is a thermodynamic process where there is no exchange of heat between the system and the surroundings. This means that Q is equal to zero. In an adiabatic process, the work done by or on the system is solely due to a change in its internal energy. Therefore, the equation Q = -w is not applicable for adiabatic processes.

Isothermal Process:
An isothermal process is a thermodynamic process where the temperature of the system remains constant throughout the process. In an isothermal process, the heat absorbed or released by the system is counterbalanced by the work done by or on the system. Therefore, the equation Q = -w is applicable for isothermal processes.

Cyclic Process:
A cyclic process is a thermodynamic process where the system returns to its initial state after completing a series of changes. In a cyclic process, the net work done by or on the system is zero, and the net heat absorbed or released by the system is also zero. Therefore, the equation Q = -w is applicable for cyclic processes.

Conclusion:
In summary, the equation Q = -w is not true for adiabatic processes since there is no exchange of heat between the system and the surroundings. However, it is applicable for isothermal and cyclic processes where there is exchange of heat and work between the system and the surroundings.