Question

Let C_v and C_p denote the molar heat capacities of an ideal gas at constant volume and constant pressure respectively. Which of the following is a universal constant?

Options

• `("C"_"P")/("C"_"P")`

• C_pC_v

• C_p − C_v

•  C_p + C_v

Answer 1

 C_p − C_v

For an ideal gas, C_p − C_v = R , where C_v and C_p denote the molar heat capacities of an ideal gas at constant volume and constant pressure, respectively  and R is the gas constant whos value is 8.314 J/K. Therefore, C_p − C_v is a constant. On the other hand, the ratio of these two varies as the atomicity of the gas changes. Also, their sum and product are not constant.