To determine which experiment's data should be changed to "No" in the column titled "Chemical reaction?", we need to analyze the evidence presented for each experiment.
Here are the steps taken:
1. Review of Provided Information:
- Experiment 1:
- Substances: Water + heat
- Evidence: Gas formation
- Chemical Reaction: Yes
- Experiment 2:
- Substances: Vinegar + baking soda
- Evidence: Gas formation
- Chemical Reaction: Yes
- Experiment 3:
- Substances: Cabbage juice + lemon juice
- Evidence: Color change
- Chemical Reaction: Yes
- Experiment 4:
- Substances: Liquid A + Liquid B
- Evidence: Precipitate formation
- Chemical Reaction: Yes
2. Criteria to Identify a Chemical Reaction:
- Typical signs of a chemical reaction include gas formation, color change, and the formation of a precipitate.
3. Analysis of Each Experiment:
- Experiment 1: Water, when heated, can result in gas formation (steam). This is a physical change, not a chemical reaction.
- Experiment 2: Mixing vinegar and baking soda produces carbon dioxide gas, which is a chemical reaction.
- Experiment 3: Mixing cabbage juice (which acts as a pH indicator) and lemon juice (acidic) results in a color change indicating a chemical reaction.
- Experiment 4: The formation of a precipitate indicates a chemical reaction between Liquid A and Liquid B.
4. Conclusion:
- Upon examining the evidence, the claim "Chemical Reaction: Yes" for Experiment 1 is incorrect, as heating water is a physical change (phase change from liquid to gas) rather than a chemical change.
- Therefore, the evidence for Experiment 3 (cabbage juice + lemon juice causing a color change) indicates a chemical reaction because the interaction of an indicator and an acid producing a color change is characteristic of a chemical reaction.
- Since we are not questioning the correctness of the other entries and focusing only on whether to change an experiment to "No," upon re-evaluating, it seems that the discrepancy could still exist around chemical knowledge where color change might occasionally be seen ambiguous without broader chemical context or solution precision.
As a result, the correct experiment whose data should be changed to "No" is Experiment 3 with the substances being "Cabbage juice + lemon juice" showing an ambiguous potential due to contextual variability in color change interpretation might warrant that deeper check.
Thus, the experiment is:
Experiment 3.
