Answer:
The difference between the energy of the reactants and the energy of the products is called the enthalpy change (∆H) of the reaction. For an exothermic reaction, the enthalpy change is always negative. In an endothermic reaction, the products are at a higher energy than the reactants.
Explanation:
The first one is 2
The second is 1
The third is 6
And the fourth is 3
The carbon is considered because it is form by oxygen atoms