how does each of the following procedural changes affects the amount of specified substance recovered?

Question

Question:

Can someone tell me how each of the following changes would affect the amount of the specified substance recovered????


1. the recovery of CaCO3 was attempted by adding 3M H2SO4 instead of 3M HCl to the SiO2 / CaCO3 residue

2. the recovery of CaCO3 was attempted by adding 1M KNO3 solution instead of 1M K2CO3 solution to the filtrate, containing aqueous CaCl2

Answer 1

1.) CaSO4 is insoluble not CaCl2, thus amount recovered by adding H2SO4 will be less than that by adding HCl

2) Common ion effect.