Amixture of very finely ground iron particles and sand particles could best be separated in lab by: a magnet adding water and filtering the metals comparing their boiling points comparing their melting points

Answer is: a magnet.

1) A magnet is attracted to magnets (ferromagnetic), sand is not.

2) Iron and sand do not dissolve in water, so if they are filtered, both substances will stay on filter paper.

3) Iron (Fe) and sand (SiO₂) boiling points are very close, around 1900°C.

4) Iron and sand melting points are very close, around 1550°C.