You should always study. you can be above your class. thats what i do.. search google for ur course. they can tell u some key points for it. u should even study what you know and want to know as well.
Answer:

Explanation:
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In this case, since calcium's oxidation state when forming ionic bonds is +2 and sulfur's oxidation state when bonding those bonds is -2, for the required formula we write:

Now, since they have the same charge number, we infer the ionic compound formed when they bond is calcium sulfide:

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I can't see the picture, but in general, I believe it is in dropping from the first energy level above the ground state, to the ground state.
B reactant +product+reactant+Product