The answer is B. making sawdust.
Because, to make sawdust you have to shred wood and you can't reverse that. Therefore, making sawdust is irreversible.
Given :
Temperature , T = 25°C = (25 + 273) K = 298 K .
The standard enthalpy change , .
The standard entropy change , .
To Find :
The standard free energy change at 25° C .
Solution :
Standard free energy is given by :
Therefore , the standard free energy change at 25° C is -502.86 kJ .
Hence , this is the required solution .
Heat will go from hot coffee to the cold cream and vise versa