1. An organic substance consisting of exlusively carbon, hydrogen, ozygen was completely burnt in excess oxygen to produce 24.91g of CO2 and 10.2g of H2O. If 11.563g of the initial substance was burnt what was the empirical formula of the substance?
my answer was = C5 H10 O2
2. If 102g of this substance burnt completely with 6.5mol of oxygen what is the molecular formula of this substance?
3. A separate sample of this substance was taken and reduced, a process which removed all oxygen atoms. What is the molecular formula for the hydrocarbon produced?
I am having a lot of trouble with the second 2 questions, if anyone can help me please do so.