the non-metal elements selenium has six electrons in its outer orbit what atoms of this element form positively charged or negatively charged ions

When a septic tank backs up a goes in to clean it out

Great amounts of electromagnetic energy from our sun and other bodies in space travel through space. which is a logical conclusion about these electromagnetic waves? their energy must be very their frequency must be very low these waves can travel without a medium they only travel through a vacuum of space

Ahypothesis must be testable and falsifiable to be considered scientific a. trueb. false