Why do you have to soak the leaf. in boiling water after heating it in alcohol​

Gunpowder residue is most likely to show up where on a shooters hands

What is the thinnest soap film (excluding the case of zero thickness) that appears black when illuminated with light with a wavelength of 480 ? the index of refraction of the film is 1.34, and there is air on both sides of the film. express your answer in nanometers. hint 1. how to approach th

Convection currents are caused by differences in what two things?