J.R. S. answered 06/22/19
Ph.D. University Professor with 10+ years Tutoring Experience
2Hg2O ==> 4Hg + O2. ... balanced eq
moles Hg2O used = 8.94 g x 1 mole/417 g = 0.0214 moles
Moles O2 that can be produced = 0.0214 mol Hg2O x 1 mol O2/2 mol Hg2O = 0.0107 mol O2
Using the ideal gas law PV = nRT, calculate volume...
V = nRT/P = (0.0107 mol)(0.0821 Latm/Kmol)(303K)/0.954 atm
V = 0.279 L
NOTE: 725 torr was converted to atm using 1 atm = 760 torr. Also 30 deg C was converted to K by adding 273.