They can enter your blood stream (via breathing/ingesting) and once in your bloodstream they can enter cells and mutate your dna, which can cause cancer/birth defects/ reproductive harm
You can use refraction which is the bending of light through a transparent material. Also the freezing and boiling points of water. One last one is the Cartesian five experiment, this shows the density of water. Hope this helped.
The substance is colder than it was because when particles move very quickly its either how or boiling so if its slow its cold and if it freezed the particles are well frozen
Rose bush because not many animals eat rose bushes
