Question

The ratio of CP and CV depends on temperature T according to relation :

Answer 1

The answer depends on the kind of material you are considering. For an ideal gas, Cpm = Cvm + R. If it is a molecular gas, increasing temperature enables vibrational degrees of freedom, so that Cvm increases. Hence Cpm/Cvm = 1 + R/Cvm decreases.

There may be an exception for hydrogen: for example, e-H2 (equilibrium hydrogen) has a peak of the heat capacity at low temperatures.

For liquids, the answer is not simple indeed.