CxHy+(x+y/4)O2=xCO2+y/2H2O~1+y/4
20 ~ 50
1 ~ 1+y/4
y=6
又X+1.5小于等于5
X＝3?2?1?
因Y＝6所以X＝3或2
C2H6或C3H6