How do you know that a sealed calorimeter is a closed system? a) because temperature is conservedb) because the masses of the sample and water are equalc) because thermal energy is not transferred to the environmentd) because work is done on the test sample

Option (c) is the correct answer.

Explanation:

When a system is open then there will be exchange of energy between the system and surrounding.

Whereas when a system is closed then there will be no exchange of energy, that is, thermal energy will not flow into the atmosphere.

Thus, we can conclude that a sealed calorimeter is a closed system because thermal energy is not transferred to the environment.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.