Gas Laws

Step 1: Understanding the Concept:
Cp is the molar heat capacity at constant pressure, and Cv is the molar heat capacity at constant volume. R is the universal gas constant.

Step 2: Detailed Explanation:
The relationship between Cp and Cv for an ideal gas is given by Mayer's relation: Cp - Cv = R. This is derived from the first law of thermodynamics, considering the work done by the gas during expansion at constant pressure.

Step 3: Final Answer:
The correct relationship is Cp - Cv = R.