What density is and what is it used for

Density measurement is used to specify and describe a pure substance, but also determines concentrations of binary mixtures and therefore gives information about the composition of mixtures. It is, for example, useful during quality control or helps determine the filling volume during the bottling of a product.

The nucleus inside an atom consists of positively-charged  protons  and neutrally-charged  neutrons. a  proton  is a subatomic particle with a positive electric charge. allprotons  are identical.