A container with 100 gram oleum is labeled as 109% by mass. % of SO3 remaining in container is ____?

Oleum is a mixture of H2SO4 and SO3Let mass of oleum be 100 gram Let mass of SO3=x  ''g Then mass of H2SO4=(100-x)gnSO3= Weight of SO3 gram molecular weight of SO3=x80SO3+H2O→H2SO4  nSO3=nH2SO4∴ mass of H2SO4 formed =98x80 mass of H2SO4 already present + mass of H2SO4 formed = Total mass of oleum (100-x)+98x80=10998x80-x=109-100  x=40 g∴40% of SO3 is remaining