Calculate the decrease in temperature when 2.00 l at 20.0 °c is compressed to 1.00 l.

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

I’m not sure what your trying to say here.. can you clarify again?