Answer: The mass of 0.004 moles of sodium hydrogensulfate is 0.568 g.
The mass of a substance can be calculated from the number of moles of the substance using the substance's molar mass. The molar mass of a substance is the mass of 1 mole of the substance, and it is typically measured in grams per mole (g/mol).
To find the mass of 0.004 moles of sodium hydrogensulfate (NaHSO4), we can use the substance's molar mass:
mass = (0.004 moles) x (142.08 g/mol)
mass = 0.568 g
So, the mass of 0.004 moles of sodium hydrogensulfate is 0.568 g. This is the mass of the substance when it is in the form of NaHSO4.