8Al + 30HNO3 → 8 Al(NO3)3+3NH4NO3 + 9H2O as per thegiven equation the number of moles of the aluminium metal that can be oxidised by one mole of HNO3 is

8Al + 30HNO3 → 8 Al(NO3)3+3NH4NO3 + 9H2O;Al → Al+3 (↑3)Of the 30 moles ions 27 moles of nitrate ions remained unchanged only 3 mole nitrate ions reduced to ionsAll the 8mole of 'Al' oxidized to Al+3So 8 moles of Al reduces 3 moles of nitrate ion'X' moles of Al reduces 3 moles of nitrate ionAlternate method Criss - Cross method8 mole of Al reduces 3moles of ions'X' mole of Al reduces 1moles of ions