Two gaseous samples were analyzed. One contained 1.2g of carbon and 3.2g of oxygen.  The other contained 27.3% carbon and 72.7% oxygen. The experimental data are in accordance with

% of carbon from 1st sample = 1.21.2+3.2×100=27.3% of oxygen from 1st sample = 3.21.2+3.2×100=72.7% of carbon and oxygen from both samples are same.Above data confirms that both samples have same composition Therefore, law of definite proportions is obeyed.