Passage IV

Barium (Ba), calcium (Ca), magnesium (Mg), and strontium (Sr) exist in their compounds as M2+ ions (Mg2+, Ca2+, etc.). When solutions of these ions are mixed with solutions containing X2- ions (SO42- [sulfate], CO32- [carbonate], etc.), salts will precipitate (form a solid) if the combination of positive and negative ions forms an insoluble (not dissolving in solution) salt, MX:

M2+ (solution) + X2- (solution) → MX (solid)

The following table summarizes the results of combining various metal nitrate solutions of equal concentrations with various solutions containing X2- ions.

22. A solution contains a mixture of equal concentrations of barium, calcium, magnesium, and strontium ions.
The procedure that would best separate the ions by precipitation (followed by filtration) would be to add X2- ion solutions in which of the following orders?

Answer and Explanation

Your Answer is

Correct Answer is J

Explanation

The question asks to separate various metal ions sequentially by reacting to generate precipitation, then look at the table, you should first use potassium chromate to separate barium ions;

Then use sulfuric acid to separate strontium ions ;

Next, ammonium oxalate is used to separate calcium ions;

Finally, sodium carbonate is used to separate magnesium ions