The answer is temperature (may be wrong)
Answer:
I think this is probably the answer you are looking for.
Explanation:
https://youtu.be/PY431ZC5uDc
The 2 represents that it is a double carbon bond
it looks like..
C-C = C-C
The answer to your question would more than likely be chemical energy, natural gas, and chemical energy. but I don't know what grade your in I'm in eighth if your below I know the answer. I'm pretty sure I had a question exactly like this last year but that was last year so if it's wrong sorry. I looked it up on Google to make sure
