CnH2n-6+O2=nCO2+(n-3)H2O
n(CO2)=20,16/22,4=0,9моль;
n(CnH2n-6)=(0,9/n)моль;
M(CnH2n-6)=12 : 0,9/n=(12n/0,9)моль;
14n-6=12n/0,9
n=9;
ответ: С9Н12.
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