How many valence electrons in the following atoms:and

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

What type of energy do chemical bonds have? what type of energy is it converted to during chemical reactions? question 15 options: chemical bonds have kinetic energy, which is converted to potential energy during chemical reactions. chemical bonds have electric energy, which is converted to potential energy during chemical reactions. chemical bonds have heat energy, which is converted to kinetic energy during chemical reactions. chemical bonds have potential energy, which is converted to heat energy during chemical reactions.

Mary is conducting an experiment on how pollution affects plant growth. how can she ensure that her data are reliable?