Which energy level has the least energy? n=1 n=3 n=5 n=7

As we go farther from the nucleus, the energy of orbitals increase. Also, the farther an electron is from the nucleus, the more repulsion it has to face because of other electrons(more screening effect) and hence it is easier to remove that electron.so n=1 which is very close to the nucleus has least energy and n=7 which is far away from nucleus has higher orbital energies.

n=1 has the least energy.

hope it helps:)

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.