A Swimming Pool Was Sufficiently Alkaline So That the Carbon

Multiple Choice

A swimming pool was sufficiently alkaline so that the carbon dioxide absorbed from the air produced a solution in the pool that was 2 × 10^-4 M in carbonate ion. If the pool originally contained 4 × 10^-3 M Mg²⁺, 6 × 10^-4 M Ca²⁺, and 8 × 10^-7 M Fe²⁺, then the precipitate that was formed consisted of ________. [Ksp values are: CaCO₃, 4.7 × 10^-9; MgCO₃, 4.0 × 10^-5; FeCO₃, 2.0 × 10^-11]

A) only MgCO₃
B) only CaCO₃
C) only FeCO₃
D) only CaCO₃ and FeCO₃
E) MgCO₃, CaCO₃, and FeCO₃