Elemental mercury was first discovered when a mercury oxide<span> was decomposed with heat. forming</span>mercury<span> metal and oxygen gas. is your anwser</span>
Answer:
Jose and Sarah are running in the cross country meet. Their skeletal and muscular systems work to move them through the course. As they run, they breathe faster and harder and their heart rate increases.
A.work together
Explanation:This should help:)
We subtract the enthalpies of the reactants from that of the products:

Since this is < 0, this is an exothermic reaction.