The molarity of HNO₃ in a sample which has density 1.4 g/mL and mass percentage of 63% is _____.
(Molecular Weight of HNO₃ = 63)

The hardness of a water sample containing 10^–3 M MgSO₄ expressed as CaCO₃ equivalents (in ppm) is ______.
(molar mass of MgSO₄ is 120.37 g/mol)

The volume (in mL) of 0.125 M AgNO₃ required to quantitatively precipitate chloride ions in 0.3 g of [Co(NH₃)₆]Cl₃ is ________.
M_{[Co(NH3)6Cl3]} = 267.46 g/mol
M_AgNO3 = 169.87 g/mol

Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in grams) of the salt required to achieve 10 ppm of iron in 100 kg of wheat is _______.
Atomic weight : Fe = 55.85; S = 32.00; O = 16.00