Please help y’all I don’t understand

2 electrons

Explanation:

If you look at the periodic table, you will see that oxygen is in group 16. If you subtract 10 from 16, you will get 6 electrons, which means oxygen has 6 valence electrons. In order to become stable, you need 8 electrons. So add 2.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.