Cuando dos o más elementos se combinan químicamente, forman una?

In 2002, the rare earth elements mine in mountain pass, california was closed because

What is the molarity of the solution produced when 145 g of nacl is dissolved in sufficient water to prepare 2.75 l of solution?

If many scientists conduct the same or similar experiments, and all obtain similar results, a can be written, which is a generally agreed-upon statement that explains and predicts how a natural phenomenon works.