How many grams of HNO3 can be produced from 400. g of No2?

I assume that NO2 is being reacted with water

First we need the balanced equation for this reaction: 3 NO2 (g) + H2O (l) = 2 HNO3 (aq) + NO (g)

Second, find moles of NO2:

(400. g NO2) / (46.01g/mol NO2) = 8.69mol NO2

Third, multiply moles by the mole ratios of NO2 to HNO3 to get moles of HNO3: (8.69mol NO2) (2mol HNO3/3mol NO2) = 5.79mol HNO3

Fourth, multiply moles of HNO3 by its molar mass: (5.79mol HNO3) (63.01g/mol HNO3) = 365g HNO3 produced