61% HNO3 (W/W) is converted  to 68%(W/W) HNO3 by             , 68%(W/W)HNO3 is converted to              % by dehydration using conc. H2SO4

HNO3(355K) & H2O(373K) differ in B.P68%(W/W) HNO3+32%(W/W)H2O form a maximum boiling AzeotropeIt further cannot be separated by Fractional distillation.68%(W/W) HNO3 on dehydration using conc.H2SO4 gives 98% (W/W) HNO3