Question

which of the following reaction is exothermic?
1. H2(g)-2H(g)
2. C (s) - C (g)
3. 2 Cl (g) - Cl2(g)
4. H2O(s) - h2o(l)​

Answer 1

Explanation:

Combustion or burning is a high-temperature exothermic redox chemical reaction between fuel and oxidant oxygen. Bond breaking requires energy to be supplied for bond dissociation so it is an endothermic process while bond formation releases energy so that the product becomes stable which is an exothermic process.