For preparing 2 lt 0,4 M HNO3 solution, how many ml HNO3 must be used from 63%(w/w) stock solution? MW HNO3 : 63 and specific gravity of stock solution: 1,4 g/ml

So you need 0.8 moles HNO3, which is 63x2=126 grams. But in your stock solution, that will be 126/.63=200 grams of stock solution, but because I am so kind and good, massing conc HNO3 is a pain, so 200g solution will be 200/1.4 ml or 143 ml. check all that. Now you need to add (acid to water), so decanter up about 1.5 liters of water, add the acid, stirring. When finishted with that, add water up to the 2.0L mark. Label the contaner, store appropriately.