Let CV and CP denote the molar heat capacities of an ideal gas at constant volume and constant pressure respectively. Which of the following is a universal constant?
For an ideal gas, Cp - Cv = R.
Here, R is the universal gas constant.
Hence, the correct option is (c).
Option (a) is incorrect since Cp/Cv = ℽ, which differs for monoatomic, diatomic or polyatomic gases. Here ℽ = ratio of molar heat capacities at constant pressure and constant volume.
Option (b) is incorrect since CpCv = ℽCv2, which is not a constant as ℽ varies.
Option (d) is incorrect since Cp + Cv = (ℽ+1)Cv, which is not a constant as ℽ varies.