Question

Which of the following pairs of aqueous solutions will form a precipitate when mixed?

A) HI + KOH
B) K₂S + HBr
C) K₂CO₃ + HNO₃
D) MgCl₂ + KOH
E) All of these solution pairs will produce a precipitate.

Group of answer choices

O HI + KOH
O K₂S + HBr
O MgCl₂ + KOH
O K₂CO₃ + HNO₃
O None of the above

Answer 1

The mixture of MgCl2 and KOH will produce a precipitate since Mg(OH)2 is insoluble, making this the correct answer. The correct answer is option d.

Step-by-step explanation:

To determine which pair of aqueous solutions will form a precipitate when mixed, we must consider the solubility rules and perform a double displacement reaction for each pair.

• HI + KOH: H2O and KI are formed, both of which are soluble.
• K2S + HBr: H2S and KBr are formed, but H2S is a gas, so no precipitate is formed.
• K2CO3 + HNO3: H2CO3 and KNO3 are formed, but H2CO3 decomposes to CO2 and H2O, so no precipitate is formed.
• MgCl2 + KOH: Here, Mg(OH)2 is formed, which is insoluble and will form a precipitate.

Given these reactions, the correct option is that the mixture of MgCl2 + KOH will produce a precipitate. So the correct answer is MgCl2 + KOH.