Question

A student mixes two clear liquids together. After a few minutes, a white powdery solid can be seen settling on the bottom of the test tube. Which of the following is a conclusion that the student can draw based on these observations?
A:The two liquids are toxic and should be handled with extreme caution.
B:The two liquids were pure substances before they were mixed.
C:The two liquids have been stored too long and are no longer good.
D:The two liquids have gone through a chemical change in which a new substance called a precipitate was produced.

Answer 1

Answer:

D

Explanation:

Answer 2

Answer:

The correct answer is D; the new substance produced is a precipitate.

Explanation:

Essentially what happened was the two liquids could not mix (insolubility), so a white powder settled at the bottom, which is called a precipitate (residue). This is evidence of chemical change and chemical reaction.