Final answer:
A Buchner funnel uses filtration to separate a mixture of solid and liquid by passing the mixture through a porous medium, such as filter paper or a semi-permeable membrane.
Step-by-step explanation:
A Buchner funnel uses filtration when separating a(n) mixture of solid and liquid by filtration. Filtration is a process that separates solids from fluids by passing the mixture through a porous medium, such as filter paper or a semi-permeable membrane. In the case of a Buchner funnel, the solid particles are trapped on the filter while the liquid passes through, resulting in the separation of the two components.