The solubility of nitrogen gas in rubber at 25°C is 0.00156 kmol/m3 · bar. When phase equilibrium is established, the density of nitrogen in a rubber piece placed in a nitrogen gas chamber at 800 kPa is
(a) 0.012 kg/m3
(b) 0.35 kg/m3
(c) 0.42 kg/m3
(d) 0.56 kg/m3
(e) 0.078 kg/m