Questions from Chapter: Nitrogen and Sulfur

[Kim Shaw]

An acidic impurity is removed from the gaseous emissions of a coal-powered power station by passing them through an aqueous suspension of mineral followed by oxidation. which of the following combination satisfies these conditions?
Acidic Impurity / Mineral / Oxidised product
A NO2 / MgCO3 / Mg(NO3)2
B P4O6 / Ca(OH)2 / Ca3(PO4)2
C SiO2 / CaO / CaSiO3
D SO2 / CaCO3 / CaSO4
Answer is D but I really don't undertand why!

 

[IndianMan]

An acidic impurity is removed from the gaseous emissions of a coal-powered power station by passing them through an aqueous suspension of mineral followed by oxidation. which of the following combination satisfies these conditions?
Acidic Impurity / Mineral / Oxidised product
A NO2 / MgCO3 / Mg(NO3)2
B P4O6 / Ca(OH)2 / Ca3(PO4)2
C SiO2 / CaO / CaSiO3
D SO2 / CaCO3 / CaSO4
Answer is D but I really don't undertand why!

First of all since an acidic impurity has to be removed it will be a basic compound that will react with it! OK?
So B and C are out of the question since the compounds aren't specially acidic gases!
So here D because SO2 is an acidic gas! And we know that CaCO3 is the material lined along the walls of the chimneys that emit the waste gases into the atmosphere and the reaction will produce CaSo4!