Let the molecular formula of Beta carotene be CxHy and the balanced equation of its combustion in excess oxygen is as follows.
CxHy+(x+y4)O2→xCO2+y2H2O
It is given that 1g beta carotene produces 3.278g CO2 and 0.9397g H2O
Molar mass of BC is 536.96g/mol
So 1 molor536.96g BC will produce 3.278×536.96≈1760.15g CO2 and 0.9397×536.96≈504.58g H2O
Molar mass of CO2=44g/mol
So number of moles of CO2 produced =1760.15g44g/mol≈40mol
Hence number of C-atoms in one molecule of BC is =40 as one molecule of CO2 contains one atom of Carbon.
Again Molar mass of H2I=18g/mol
So number of moles of H2O produced =504.58g18g/mol≈28mol
So one mole BC produces 28mol water which contain 56 mol atom Hydrogen as one molecule of water contains two atoms of Hydrogen.Hence number of Hydrogen atom present in one molecule of BC is 56.
Now we can say that molecular formula of BC is C40H56