0.28 g of an organic compound in Dumas method liberated 22.4 ml of nitrogen at STP. The percentage of nitrogen in the compound is

The CO2 , H2O released in the above equation absorbed into aq. KOH solution which is taken in nitrometer. The N2 gas collected at the top of the nitrometer [graduated tube]. The volume of N2 collected in graduated tube is called experimental volume, which is denoted by "V1"  [vml].→ Experimental volume we need to convert into STP volume