Value of R gas constant in J mol-1 K-1 is
Correct answer: A. 8.314
- A. 8.314
- B. 62.4
- C. 0.821
- D. 62400
Explanation
The universal gas constant is 8.314 joules per mole per kelvin, and this is the value to use whenever pressure is in pascals and volume in cubic metres. The figure 0.0821 dm3 atm per mole per kelvin is the same constant expressed for pressure in atmospheres, which is why 0.821 appears as a distractor. Always match the value of R to the units of the other quantities in the problem.
This question appeared on the UHS MDCAT 2025 paper, which you can sit online with every answer explained.
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About Ideal Gas Equation
The ideal gas equation, PV = nRT, relates pressure, volume, amount and absolute temperature when gas particles are assumed to have negligible volume and no intermolecular forces. Applications include finding molar mass, density or an unknown gas variable, with careful use of Kelvin temperature and consistent units, and comparison with real-gas behaviour.
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