Which of the following is kept constant when using a coffee cup calorimeter? temperature density mass pressure

The answer is pressure

Pressure

Explanation:

A coffee-cup calorimeter is essentially a constant-pressure calorimeter which is  used to measure the enthalpy change (ΔH) in a solution. It comprises of a system of 2 nested styrofoam cups containing water which absorbs the heat from the reaction. A thermometer is inserted through the lid of the cup to record the changes in temperature.

Thus, the heat flow measured at constant pressure, q(p) is the enthalpy change (ΔH) of the reaction

The amount of heat absorbed or evolved during a reaction is related to the mass of the substance(m), specific heat capacity (c) and the change in temperature, ΔT

what are the two models

explanation:

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a