D.
If we take a sample of 100g of the given compound, we should find that it contains 74.1g of oxygen and 25.9g of nitrogen. The molar masses of oxygen and nitrogen are approximately 16.0g/mol and 14.0g/mol respectively. To find the appropriate number of moles of oxygen and nitrogen found in one mole of the given compound, we divide the mass of the sample by the molar mass of each substance.
For oxygen: 74.1g/(16.0g/mol) = 4.63125 mol (round up to 5 mol)
For nitrogen: 25.9g/(14.0g/mol) = 1.85 mol (round up to 2 mol)
Therefore one mole of this compound contains 2 moles of nitrogen and 5 moles of oxygen.
