The purity of a solid sample can best be determined by its

The melting point of a solid sample is the most reliable way to determine its purity. The melting point of a pure substance is a fixed temperature, which is well defined and does not change with time. If there are impurities present in the sample, the melting point will be lower and will not be a fixed temperature. By measuring the melting point, we can determine the purity of the sample. If the melting point is lower than expected, it indicates the presence of impurities in the sample. This is because impurities lower the energy needed to break the bonds holding the solid together, allowing it to melt at a lower temperature.