The evidence that a chemical reaction occurred is can be change in color , formation of a precipitate , Here in the case when 6 m HCl to the solution of sodium acetylsalicylate, the formation of precipitate that is of aspirin takes places that can be taken as a evidence that a reaction is occured. The reaction can be seen in the image attached.
I think the answer is magnetic field?
The molarity of the solution will be 0.72 m.
The majority of reactions take place in solutions, making it crucial to comprehend how the substance's concentration is expressed in a solution when it is present. The number of chemicals in a solution can be stated in a variety of ways, including.
The symbol for it is M, and it serves as one of the most often used concentration units. Its definition states how many moles of solute there are in a liter of solution.
Given data:

Molarity can be determined by the formula:

where, M is molarity and V is volume.
Put the value of given data in above equation.
57.3 × 0.497 m = M × 39.5 L
M = 0.72 m
Therefore, the molarity of the solution will be 0.72 m
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