To calculate the enthalpy of combustion of methane gas CH4 , we need to first determine the number of moles of methane in 1.0 g and then use the heat released to find the enthalpy change per mole.The molar mass of methane CH4 is:C: 12.01 g/molH: 1.01 g/molMolar mass of CH4 = 12.01 + 4 1.01 = 12.01 + 4.04 = 16.05 g/molNow, we can find the number of moles in 1.0 g of methane:moles = mass / molar massmoles = 1.0 g / 16.05 g/mol = 0.0623 molThe heat released -890 kJ is for 1.0 g of methane, which is 0.0623 mol. To find the enthalpy of combustion per mole, we can use the following equation:enthalpy of combustion = heat released / molesenthalpy of combustion = -890 kJ / 0.0623 mol = -14288.6 kJ/molTherefore, the enthalpy of combustion of methane gas CH4 is approximately -14,289 kJ/mol.