What are three separation techniques to separate iron filings, salt and sand?

First Magnetic Separation to remove the iron fillings.

Next Dissolution of the sand and salt in water, and Filtration to separate the salt solution from the sand.

Evaporation of the salt solution to get back the salt.

Exothermic,  physical change after it is already baked

Both models are effective because they show the valence electrons, and these valence electrons indicate the reactivity of an element.