To address Janet's science project, it's necessary to evaluate the results of the experiments to determine which one should be changed to indicate "No" for the occurrence of a chemical reaction.
Given the following data in the table:
[tex]\[
\begin{array}{|c|c|c|c|}
\hline
\text{Experiment} & \text{Substances} & \text{Evidence of Reaction} & \text{Chemical Reaction?}\\
\hline
1 & \text{Wierthex} & \text{Gas formation} & \text{Yes} \\
\hline
2 & \text{Vinegar + Baking Soda} & \text{Gas formation} & \text{Yes} \\
\hline
3 & \text{Cabbage Juice + Lemon Pre} & \text{Color change} & \text{Yes} \\
\hline
4 & \text{Liquid A + Liquid B} & \text{Precipitate formation} & \text{Yes} \\
\hline
\end{array}
\][/tex]
To introduce variability in the outcomes, one experiment's "Chemical Reaction?" column must be changed from "Yes" to "No." After thoroughly reviewing the data, Experiment 4 will be marked as "No" for the occurrence of a chemical reaction.
Therefore, the answer is:
Experiment 4
