How could you separate a mixture of water, rock salt, sawdust, and iron filings? Would this require physical means, chemical means, or both?

Answer 1

Iron filings are magnetic. Use a magnet.
saw dust floats on water. Use a skimmer.
Evaporate H2O and rock salt is left. If you wish to recover the water you can distill the water/rock salt mixture and collect the water. The rock salt stays behind in the distillation flask.