1. The problem statement, all variables and given/known data Hi, Im not sure about the following question: (Q) Argon (atomic weight 40) exists as a monatomic gas at room temperature and pressure. The density of liquid argon is 1784kg/m^3. (a) Calculate the atomic density (atoms/m^3) in liquid argon *Done* (b) Hence assumming the packing fraction in liquid argon is 0.7, determine the radius of an argon atom. *Done* (c) calculate the atomic density in gaseous argon at a pressure of 1atm and a temperature of 300K *Done* (d) hence calculate the mean free path of an argon atom at a pressure of 1 atm and a temperature of 300K? 2. Relevant equations It is part (d) which I'm having trouble with The mean free path formula is 1/[(4pi)nσ²] 3. The attempt at a solution For part (d) which 'n' should I use the one for gas argon or for liquid argon, the question given doesnt seem to state which mean free path to calculate?