When an electron de-excites from the third quantum level to the second, and then to the ground state, two photons are emitted. the sum of the emitted frequencies equals the frequency of the single-photon that would be emitted if de-excitation were from the third to

ground state

Explanation:

  Lets take  

n=3 ,n=2 ,n=1 are the energy level.

Energy level n=1 is the ground energy level.

The energy from 3 to 1 = hν

The energy from 3 to 2 = hν₁

The energy from 2 to 1 = hν₂

We can say that

hν = hν₁ +  hν₂

If the electron were de-excitation from the third level to ground level then the sum of emitted frequency will be equal to the frequency of a single electron.

Therefore the answer is ground state.

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.

increases it