Final answer:
Yes, the formation of a purple powder when two liquids meet is evidence of a chemical reaction, as it shows a color change and the formation of a precipitate. So, the correct answer is A.
Step-by-step explanation:
When drops of one liquid are added to another liquid and a purple powder forms where the liquids meet, this indicates a chemical change has occurred. This formation of a precipitate, alongside the color change that is described, are both classic signs of a chemical reaction. In this scenario, the correct answer would be a) Yes, the two liquids did enter a chemical reaction.
Evidence of a chemical reaction includes the formation of a precipitate, a color change, or the emission or absorption of heat. Mixing two colorless solutions to form a yellow precipitate is a clear illustration of such a reaction. The starting materials have changed their chemical properties to form a new substance, which is fundamental to the definition of a chemical reaction.