How can compounds and mixtures be broken down?

For compounds, we can use simple reagent/conditions such as i) Heat. Heat can pretty much decompose any compounds, given enough of it (correct me if I am wrong, my fellow quorans) e.g. heating CaCO3(s) breaks it down to CaO(s) and CO2(g). read more

cannot be broken down into a simpler type of matter by either physical or chemical means, and; can exist as either atoms (e.g. argon) or molecules (e.g., nitrogen). A molecule consists of two or more atoms of the same element, or different elements, that are chemically bound together. read more