Could you attach a picture because I can tell you didn't post the entire question.
The answer is 27.92g . working is shown in the picture above.
Precipitation :)
Hope it helps
The standard atomic weight of a C is 12, and the standard atomic weight of a H is 1. So to find molar ratio of C and H in the compound: 60.0/12=5, 5.05/1=5. This means the molar ratio of C and H is 5:5, thus 1:1. Assuming the molecular formula is CnHn, to find molar mass: 12n + 1n = 78.12. n=78.12/(12+1) = 6. So the compound's molecular formula is C6H6, benzene.
The combustion of 1 mole of methane (CH4) in a domestic furnace requires 2 moles of O2 molecules, assuming the combustion was complete or ideal. To solve this problem, use stoichiometry of the reaction's balanced chemical equation:
CH4 + 2O2 --> CO2 + 2H2O
The ratio of CH4 to O2 in terms of moles is 1:2. So 1 mole of CH4 needs 2 moles of O2.