The components of a mixture are most efficiently separated from one another basaed upon their;?

Question

The components of a mixture are most efficiently separated from one another basaed upon their;?

Answer 1

Grain size.

Answer 2

Depending on the characteristics;

Density

magnetism

electrical conductivity

solubility

size separation (screening)

temperature (freezing or volatilizing

Chemistry

And so on, depending on what is in the mix.

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Answer 3

weight,either by centrifuge or gravity

Answer 4

Miscibility?  Efficiency would be a function of the separation process-what is the reason for the separation?

Oil and water mixtures will separate naturally in absence of external disturbance.

Sediment loads will separate as the function of the energy of the system that is causing the mixing.

Water (which could be considered a mixture of regular and "heavy" water, although strictly speaking mixture is not the approriate term I suppose, more a solution)  can be separated into isotopically distinct components through cascading chemical reactions that produce progressive fractionation.

Alcoohol-water solution (again the mixture issue) can be separated by fractional distillation.

In mineral processing, there are several steps in the separation of the initial bulk mixture that involves grain size screening, mass (density as a proxy although it is really mass separation, like in a jig or spirals) separation, and chemical separation (as in mineral flotation or leaching-precipitation, or leaching adsorption)

Obviously the question has a context which would lead to an implied answer.  In and of itself, the question has no specific answer.