What evidence proves that energy and molecules are being transferred (moved throughout this aquaponics system?

In an oxidation-reduction reaction, oxidation is what happens when a reactant

What shape would a molecule with two bound groups and two lone pairs have?

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.