An Industrial Plant Processes Its Waste Water Through a Sedimentation $\approx$

Multiple Choice

An industrial plant processes its waste water through a sedimentation tank that removes hazardous metals by precipitating them as insoluble carbonate salts.If sodium carbonate is gradually added to the tank,what would be the order of precipitation of the metals,Pb²⁺,Cu²⁺,Hg₂²⁺,and Zn²⁺ if each is $\approx$ 1.0 $\times$ 10^-4 M? ( K_sp PbCO₃ = 7.4 $\times$ 10^-14,K_sp CuCO₃ = 1.4 $\times$ 10^-10,K_sp Hg₂CO₃ = 8.9 $\times$ 10^-17,and K_sp ZnCO₃ = 1.4 $\times$ 10^-11)

A) Pb²⁺,Hg₂²⁺,Zn²⁺,Cu²⁺
B) Hg₂²⁺,Pb²⁺,Zn²⁺,Cu²⁺
C) Cu²⁺,Zn²⁺,Pb²⁺,Hg₂²⁺
D) Cu²⁺,Zn²⁺,Hg₂²⁺,Pb²⁺
E) All metal ions will precipitate at the same time.