The Amount of Calcium Present in Milk Can Be Determined

Multiple Choice

The amount of calcium present in milk can be determined by adding oxalate to a sample and measuring the mass of calcium oxalate precipitated. What is the mass percent of calcium if 0.429 g of calcium oxalate forms in a 125-g sample of milk when excess aqueous sodium oxalate is added? Na₂C₂O₄(aq) + Ca²⁺(aq) → CaC₂O₄(s) + 2Na⁺(aq)

A) 0.107%
B) 0.202%
C) 0.343%
D) 1.10%
E) 1.37%