Is it possible using the styrofoam calorimeter for the temperature to decrease when a solid is added to water in one of the calorimeter wells?

Yes

Explanation:

It is possible for the Styrofoam calorimeter to experience a temperature decrease when a solid is added to the water. This is because of the phenomenon called thermal shock. In this phenomenon, there is a slight transfer of energy from the hot fluid to the solid. At the same time, there is the gain of energy by the cold solid since energy flows from higher temperature region to a lower temperature region. This decrease in temperature happens until equilibrium is reached in the system. From there, there will be a stabilization in the temperature.

the second awnser

explanation:

because it is for complex problems