Rainbows go in the order of ROYGBIV, which is an acronym for red, orange, yellow, green, blue, indigo, violet.
So, it would start off with red.
If you want to know why it starts off the rainbow, its because red has the longest wavelength, compared to the rest of the colors. (sorry I'm rambling, I got excited)
Hope this helps.
The gallionella bacteria reaction
that is Fe2+ → Fe3+ is example of oxidation reaction (answer A)
Explanation
oxidation reaction reaction occurs when electrons are lost during reaction by a molecule or ion or atom. when oxidation occurs the oxidation state of the molecule or ion or atom increases. For this reason Fe2+ → Fe3+ is a oxidation reaction since the oxidation state move from oxidation state 2 to 3
Oxygen and selenium both have 6 valence electrons. They're in the same group hope this helps
Static electricity. they have the same charge and same charges repel each other.