A) Ar at 100 torr and 300 K. b) H2 O at 1.0 atm and 90 23. Which of the following gases is least likely to behave like an ideal gas? A) Ar at 100 torr and 300 K. b) H2 O at 1.0 atm and 90 C. c) N2 at 1.0 atm and 90 C. d) H2 at 1.0 atm and 900 C. e) He at 1.0 torr and 90 C. 24. You have carefully placed 0.100 mole of an unknown gas in a 10.0 liter container at exactly 323 K and measured the pressure.