Respuesta :

Use ideal gas equation:

n = PV / RT

P = 100kPa = 100 x 1000 x (9.8 x 10^{-6}) = 0.98 atm
convert kPa to atm. 1 Pa = 9.8 x 10^{-6} atm
T = 293 K
V = 6.8 L
R = 1/12
put all values.
So, n = 0.272