Answer:
Red light has the longest wavelength
Explanation:
Red light is emitted when a high energy state electron drops from high energy level 3 to low energy level 2. Red light has the longest wavelength and lowest energy. It is a know fact that the shorter the drop within energy levels, the lesser the energy.
He used prisms to demonstrate how white light is in fact made
Seven elements make up the compound
In order to determine whether a bond is ionic or covalent, you need to know whether or not it is completely composed of nonmetal atoms or both metal and nonmetal ions.
Barium is a metal and Oxygen is a nonmetal, therefore there is no possible way they could bond unless they were attracted to opposite charges. Specifically, only if Barium becomes a cation and Oxygen becomes an anion then could they bond.
Now cation and anion both have the word "ion" in them, so therefore it must be an ionic bond.
Now we need to know the definition of a bond. A bond is formed when two elements are joined together by sharing their valence electrons.
Therefore, your answer should be:
Ionic, because valence electrons are shared.
Power source (battery/energy) a copper/metal wire, and then a receiver
