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Question
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?
Options
`("C"_"P")/("C"_"P")`
CpCv
Cp − Cv
Cp + Cv
Solution
Cp − Cv
For an ideal gas, Cp − Cv = R , where Cv and Cp 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, Cp − Cv 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.
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