¿Por que se dice que las personas formamos parte de un ecosistema?

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

You may expect bonds between two atoms which each have n covalent lonic metallic hydrogen

Working with si (metric) units for each of the following commonly used measurements, indicate its symbol. liter gram milliliter kilogram meter centigram milligram centimeter kilometer second millimeter milliseconds