1. The problem statement, all variables and given/known data If the volume V and pressure P of an ideal gas decrease, which statement is true about the internal energy IE, temperature T and the intermolecular forces IF? (I am not gonna copy and paste the choices here in an effort to focus attention on the attempt of solution.) Would greatly appreciate if anyone can point out an error in thinking! 2. Relevant equations Change in Internal Energy (I.E.) = Q (heat added) + W (done on system) PV/T = PV/T 3. The attempt at a solution First: My final answer. (Incorrect) IE increases, T increases, IF are unchanged Since P and V decrease, by P1V1/T1 = P2V2/T2, the temperature of this ideal gas should decrease. Since Kinetic Energy is directly proportional to KE, the Internal Energy of the system should increase! (In an ideal gas: no Intermolecular forces, otherwise, the gas would liquefy!) So, Internal Energy is composed of KE, and since Temperature goes up, IE goes up, and IF is constant (or zero). Many thanks in advance !