What is the scientific definition of a pure substance?

A pure substance is defined scientifically as a material that consists of only one type of particle, which means it is either a single element or a single compound. This definition emphasizes the fact that a pure substance does not have any other substances mixed in with it, which distinguishes it from mixtures.

For example, table salt (sodium chloride) or distilled water are pure substances because they are made up entirely of sodium chloride ions or water molecules, respectively, without any other substances present. In contrast, options describing mixtures or those containing impurities fail to meet the strict criteria for purity, which necessitates the absence of any other components. Understanding this definition is crucial for distinguishing pure substances from mixtures and recognizing their significance in various scientific contexts.