The purity of a substance can be estimated by comparing its melting point range to the literature value of the pure substance's melting point. A pure substance typically has a sharp melting point, while impurities can cause the melting point to be lower and have a broader range.In this case, the melting point range of the unknown substance is 125C to 130C, and the literature value for the pure substance is 132C. Since the melting point range of the unknown substance is lower and broader than the literature value, it indicates that the substance is impure.However, it is not possible to provide an exact percentage of purity based on this information alone. To determine the purity more accurately, additional analytical techniques such as chromatography, spectroscopy, or elemental analysis would be required.