Explanation :
It is given that In the fishbowl, the glass, water, rocks, and plastic plants are in thermal equilibrium. Thermal equilibrium is defined as the condition when all particles of the system are at the same temperature.
The temperature of the water is 75 degrees. So, using the concept of thermal equilibrium it is clear that the temperature of all the elements present inside fish bowl will be the same as that of water.
So, the temperature of the rocks is 75 degrees F.
