you can look at magnesium, it can react with oxygen to form oxides. (chemical) it is malleable and a solid at room temperature. (physical)
to measure its density, the mass and volume can be worked out and from this density too. look up the equation, it is quite easy :)
physical changes -- it can be melted, and oxidized
the chemical changes of oxidation magnesium looses electrons to form oxides, this is a chemical reaction- chemical change..--- use to get the density use (rho) or density D = M/V
