Limestone (CaCO₃, 100

Multiple Choice

Limestone (CaCO₃, 100.09 g/mol) is present in many sedimentary rocks.Suppose the limestone in a 5.000 g rock sample is dissolved in hydrochloric acid, and then 33.30 mL of 0.1500 M Na₂C₂O₄ is added to precipitate the Ca²⁺ ions as CaC₂O₄ (128.10 g/mol) .What is the mass percent limestone in the original rock sample?

A) 10.00%
B) 12.80%
C) 17.35%
D) 85.31%
E) 66.67%