Final answer:
The approximate molarity of the solution where Vasona plate pieces remain unchanged is 0.5 M, as it matches the characteristics of a 1:1 electrolyte solution with conductivity between 1.0 to 1.3 mA.
Step-by-step explanation:
The question refers to calculating the molarity of a solution, which is a concept in chemistry. Molarity is a measure of concentration that indicates how many moles of solute are present in one liter of solution.
Based on the provided information, the Vasona plate pieces not changing suggests the solution's conductivity falls within a range characteristic of a 1:1 electrolyte, leading us to infer that option c, with a 0.5 M concentration, is the most reasonable choice.
This is supported by the accompanying information which indicates that the solution has a molarity between 1.0 to 1.3 mA, matching the characteristics of a 0.5 M solution.