What is the purpose of the scale on a map

Match the mixture with the substance// i really need on this guys (it’s a pic btw)

Chortling is used to clean water. another possible atom that would also work is a. sodium b. sulfur c. bromine

An isotope undergoes radioactive decay. the new isotope that forms has an atomic number fhat is 2 less than the original isotopes. which kind of decay has occured and how do you know