Question

Choose a substance you're familiar with. what are its physical and chemical properties? How would you measure its density? What are some physical and chemical changes it can undergo?

Answer 1

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