In an atom, the first energy level can hold electrons. the second energy level can hold electrons. the third energy level can hold electrons.

2, 8, 18

Explanation:

The number of orbitals for any level of interest n is calculated by a formula . Since each orbital contains a maximum of 2 electrons, we can calculate the total number of electrons in an nth orbital by .

b.final

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.