The answer to this question is C
This separation technique is a 4-step procedure. First, add H₂SO₄ to the solution. Because of common ion effect, BaSO₄ will not react, only Mg(OH)₂.
Mg(OH)₂ + H₂SO₄ → MgSO₄ + 2 H₂O
The aqueous solution will now contain MgSO₄ and BaSO₄. Unlike BaSO₄, MgSO₄ is soluble in water. So, you filter out the solution. You can set aside the BaSO₄ on the filter paper. To retrieve Mg(OH)₂, add NaOH.
MgSO₄ + 2 NaOH = Mg(OH)₂ + Na₂SO₄
Na₂SO₄ is soluble in water, while Mg(OH)₂ is not. Filter this solution again. The Mg(OH)₂ is retrieved in solid form on the filter paper.
Calcium nitrate is limiting reactant, since it says there’s excess HCl. So you must use the mass of calcium nitrate in your calculation (see picture below):
To determine the concentration of the solution of sulfuric acid, the chemist should perform titration with the use of 1.0 M NaOH. This is the answer in the space provided. The 1.0 M NaOH is suitable in the titration because it is a base, which is used in titration in order to determine the unknown concentration.