An atom in an excited state a. has more energy than it does in the ground state b. has one more electron than it does in the ground state c. is more stable than it is in the ground state d. has less energy than it does in the ground state

The answer should be A, has more energy than it does in the ground state. De-excitation is removing electrons, so excitation would be adding more in to make it more stable. The ground state is what is considerd stable.

ANSWER: A

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.