M=44*2=88 g/mol
n=26.4/88=0.3 mol
n(CO2)=66/44=1.5 mol
n(H2O)=32.4/18=1.8 mol
N(C)=1.5/0.3=5
N(H)=2*1.8/0.3=12
88-5*12-12*1=16
即N(O)=1
所以分子式为C5H12O