A sample of fuming sulphuric acid containing `H_(2)SO_(4), SO_(3)` and `SO_(2)` weighing `1.0 g` is found to require `23. 47 mL` of `1.0N` alkali for its neutralisation. A separate sample shows the presence of `1.5% SO_(2)`. Find the percentage of free `SO_(3),H_(2)SO_(4)` and combined `SO_(3)` in the sample.