What is the percent composition of magnesium (mg) in mgo?

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

Asingle atom of an element has 21 neutrons, 20 electrons, and 20 protons. which element is it? ok o z

All of the following are part of the biosphere except