Answer: experiment 1.
Justification:
The table displays the experiment in the first column, combination of substances in the second column, the evidence of reaction in the third column, and the conclusion about whether the process is a chemical reaction or not in the fourth column.
Correctly, the table shows for the substances in experiment 2, experiment 2, and experiment 3, that the evidence indicates that the process is, indeed, a chemical reaction.
Those evidences include gas formation, color change and precipitate formation. Such evidences indicate the occurence of chemical reactions because they mean the formation of a new substance (product) with entire different chemical composition of those of the reactants.
Nevertheless, in the first row (experiment 1) the substances include water plus heat. In this case, the water is not being decomposed by the heat. This is, the substance, water, is the same, it has the same chemical composition (H₂O), before and after the heating process. The gas formation observed as product of the process is not a new different substance, it is just bubbles formed when the water reached the boiling point, which caused that the water passed from liquid state to gas. This kind of change, passing from liquid to gas, is a physical change, not a chemical reaction.