A student observes what happens when two different aqueous solutions are mixed in a test tube. Which of the following observations would be most indicative of a precipitation reaction?

a. Gas bubbles are produced.

b. A solid settles out.

c. There is a color change.

d. The test tube warms.

B

Explanation:

In precipitation reaction, there is the emergence of a solid settling out of the solution. It can be visualized as a case in which a particular soluble solid becomes insoluble due to its reaction with another substance otherwise tagged as the precipitating reagent

It is thus reagent that draws it out of the solution by making it insoluble in its former solution. Hence it acts like it is calling out the substance by using a precipitating reagent