When an enzyme is kept at sub-zero temperature, it gets inactivated and it cannot catalyse the chemical reaction. Hence, P will not occur. When this enzyme is thawed (warmed) and brought back to normal temperature, the enzyme will become active and reaction Q will occur. However, when enzyme is heated beyond 60$℃$ , it undergoes denaturation. The tertiary structure, which is absolutely essential for the activity of enzyme, is destroyed, and hence, reaction R will not occur. When this heated enzyme is cooled down, the tertiary structure cannot be regained back, and it is still non-functional. Hence, reaction S will not occur too.