We assume that this substance is in an ideal state. Then, we can use the ideal gas equation which is expressed as: PV = nRT. Comparing the first and second conditions of the substance, we can say that the number of moles and the pressure remains the same. We can solve the problem as follows:
P1V1 = n1RT1
P2V2 = n2RT2
Since P and n are the same for the conditions, we can combine the equations.
T1/V1 = T2/V2
20.0/2 = T2/1
T2 = 10.0 °C
