A multiple choice question came up before me which is as follows; "An ideal gas with initial pressure 'P' is compressed isothermally such that the mean separation between molecules is bought to half the original value. What is the new pressure of the gas?" A - P B - 2P C - 8P D - 4P Now a friend told me that the the mean separation between molecules is proportional to the volume. Going by that rule the volume of gas should halve and the pressure should simply double. He, hence, stated the answer as B. I, however, had a different approach. I seem to think that the mean seperation between molecules considers motion in only one dimension and since we are considering the volume of the gas, halving the mean separation should decreas the volume by a factor of (1/2)^3 i.e 1/8 and not just 1/2. I therefore chose the answer C. Who is correct? Did I overthink the question?
