The law of conservation of mass states that in any closed system the mass of the system is neither created nor destroyed over time i.e, the mass cannot be changed overtime.
Ribosomes are present in prokaryotic cells. These are organelles which consist of two subunits. They are present in both Eukaryotic and Prokaryotic cells. They are made up of RNA and proteins and present in the cytoplasm and on the membranes and are involved in protein synthesis.