How can the property of magnetism be used to you identify two gray minerals?

The magnet will connect to iron and another substance so that you'll know because a magnet will connect to iron for example if little iron segments are mixed with sand if u put a magnet in it it will take out all the iron segments seperating it making it so you only have the iron segments on the magnet

Lexy is correct because angle r is between the incident wave,  n  = 0, and a diffracted wave.