Question

how will you prove repulsion is the sure test of magnetism

Answer 1

Repulsion is the surest test because any substance made of iron,nickel, cobalt will also have attraction but won't have repulsion. hence the repulsion is the surest test of magnetism

Answer 2

Because when two magnetic objects are placed together the similar poles will repell each other and opposite poles of the magnet will attract each other therefore when a non magnetic object is placed together both the similar and opposite poles will attract each other .