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 300 kPa is
(a) 0.005 kg/m3
(b) 0.018 kg/m3
(c) 0.047 kg/m3
(d) 0.13 kg/m3
(e) 0.28 kg/m3