When more than one method is used to separate components of a mixture; the mixture may still contain______.

Often one method is not enough to separate all the components of a mixture. In such a case, more than one method is needed to separate them. For example, to separate sand and salt, the process involves more than one method. That is- decantation, filtration, evaporation, and condensation. Here, even after the filtration and decantation, the decanted liquid contains salt in the water. Therefore, it is very much possible that even more than one method is used to separate components of a mixture; the mixture may still contain two or more components.