Which of the following pairs of compounds would form a precipitate when their aqueous solutions are mixed?
The correct answer is: C
Explanation
when potassium sulfate is mixed with barium chloride a white precipitate of barium sulfate will be form. barium sulfate is slightly soluble in water, so it will precipitate out as a solid
BaCl2 + K2SO4 → BaSO4 + 2KCl
note; all substances are aqueous except BaSO4 which is solid