it only happensonce every 7 years
I'm not sure but i would say C.storing the heat energy.
C, potassium. Hope this helps.
Answer:
The balanced single displacement reaction between aluminum and copper sulphate is as follows.

Explanation:
The given ions are as follows.
- Aluminium ion and copper sulfate ion.
Single displacement reaction occurs one element replaces another element.
Hence, the balanced chemical reaction is as follows.

<u>Oxidation half reaction:</u>

Aluminium loses three electrons.
<u>Reduction half reaction:</u>
<u>
</u>
Copper gain three electrons.
Here try this presentation, it should help :)
https://prezi.com/6ofdo3fadl9a/exothermic-and-endothermic-reactions-in-everyday-life/