Manipal Entrance Test 2016 Chemistry Paper

Suppose the chemical formula of the compound be CxHyOz chemical reaction related to combustion of the compound. since, 2 molecules of CO2 have 2 atoms of carbon and these carbon must have come from the compound.
Hence, the value of x is 2. Again, 2 molecules of steam contain 4 atoms of hydrogen and they have come from the compound. Hence, the value of y will be 4. Again, total oxygen atoms in the product side =6 But 4 oxygen atoms must have come from the oxygen molecules. Hence 2 oxygen atoms definitely come from the compound. Hence, the value of z=2. So, the molecular formula of the compound is C2H4O2.