Question

mechanical separation
what method would most efficiently separate 100 kg of a mixture of similar looking iron and aluminum nails?
place both nails in oil because iron will float and aluminum will sink.
use a magnet because iron metal is magnetic and aluminum metal is not.
shine uv light on both nails because iron will glow and aluminum will not.
carefully pick out each aluminum nail and iron nail and separate by by hand.

Explanation:

Iron is a ferromagnetic material that is attracted to magnets, while aluminum is non-magnetic. This physical property difference allows for quick, efficient separation of large quantities (100 kg) of the nail mixture. The other options are incorrect: iron is denser than aluminum and would sink in oil, UV light does not distinguish these metals, and hand-sorting is highly inefficient for 100 kg.

Answer:

B. Use a magnet because iron metal is magnetic and aluminum metal is not.