2no(g) + o2 (g) --> 2no2
how many moles of o2 are required to produce 46.0 g no2?

moles of NO₂ =  
      
                      =   
        
                      =    1 mol

ratio of NO₂   :    O₂      =    1   :   2

∴  since mole of NO₂  =   1 mol
          the mole of O₂  =   mol
                                   =   0.5 mol

Adialysis unit requires 78.5 l of water.the estimated digit is 5.