Given that,
Mass of carbon dioxide = 4.4 g
Molar mass of carbon dioxide = 44 g/mol
Mass of methane = 3.2 g
Molar mass of methane = 16 g/mol
Now
Number of mole of methane, nCH4 = 3.2/16 = 0.2 mol and number of mole of CO2 nCO2 = 4.4/44 = 0.1 mol Since,
PV = (nCH4 + nCO2) RT
Or, P × 9 = (0.2 + 0.1) × 0.0821 × 300
Or P = 0.3 × 0.0821 × 300/ 9 = 0.82 atm
Hence, the total pressure exerted by the mixture is 0.82 atm.