Which statement about the laws of thermodynamics is false?

The statement that refrigeration requires no external work supply is false because refrigeration systems operate by transferring heat from a colder area to a warmer area, which contradicts the natural flow of heat. To achieve this, the refrigeration cycle relies on external work, typically supplied by a compressor that circulates refrigerant through the system. In doing so, the work input is necessary to remove heat from the refrigerated space and expel it to the environment, thus maintaining the desired temperature in the colder area.

The other statements accurately represent principles of thermodynamics. Heat and work being mutually convertible reflects the first law of thermodynamics, which states that energy can be transformed from one form to another but cannot be created or destroyed. The assertion that heat supplied equals the increase in internal energy plus work done aligns with the first law as well, as it considers the energy balance in a closed system. Lastly, the principle that heat flows from a hot substance to a colder one is a fundamental observation consistent with the second law of thermodynamics, which describes the direction of natural processes.