Advantage of drinking hard water

What is a scientific theory? a. a scientist's guess about how something works b. the results of an experiment obtained using the scientific method c. a proven fact that will never change d. an idea that is backed by data from many sources

Your friend offers to show you an intrusive igneous rock. which of the following would you expect to see?

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)