What we can seprate sand and iron flings

Magnetic separation

Explanation:

Sand is non-magnetic whereas iron fillings can be used as magnets. So, they can be separated by a method which uses a magnet for separating a mixture. Magnetic separation is the process which uses magnetic force for the extraction of magnetic material from a mixture.

through magnet

although not writable answer but for gk even a blow of wind shall do

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)