18 moles of water are produced in the above reaction.
Hope this helps you!
In an exothermic reaction, heat is produced along with products. But in endothermic reaction, heat is absorbed. If the number of products is less than the sum of the enthalpies of the reactants, the reaction will be exothermic. If the number of products is more than the sum of the enthalpies of the reactants, the reaction is endothermic.
Most elements on group 18 are the Noble Gases. They already have a complete last level with 8 electrones. Actually they can form compounds but only on the lab and they will not even last half a second.