How many grams would be in four 4 moles of nitric acid HNO3?

Use the Equation

Moles = mass(g) / Mr (Relative molecular mass).

Algebraically rearrange

mass(g) = Moles X Mr

We have

4 moles

Mr(HNO3) is

From the atomic masses in the Periodi Table

1 x H = 1 x 1 = 1

1 x N = 1 x 14 = 14

3 x O = 3 x 16 = 48

1 + 14 + 48 = 63

Substitute in

mass(g) = 4 x 63

mass(HNO3) = 252 grams.

NB Bearing in mind that nitric acid is usually dissolved in water , the mass of 4 moles will be greater than 252 grams, in order to account for the mass of solvent(water).