For an ideal monatomic gas, the molar specific heat at constant volume, Cv=3/2R, where R is the gas constant. The heat capacity at constant volume of a gas is measured to be 43.58kJK-1. How many kg-moles of the gas are present? Iv tried looking in the lecture notes and in the textbook, but cant find anything of use. Iv made an attempt and got 3.5kg-moles. Not sure that its right though. I used R=kNA, where k is Boltzmann constant and NA is Avogadros number.