The Balmer series for the H-atom can be observed:
| a. | if we measure the frequencies of light emitted when an excited atom falls to the ground state |
| b. | if we measure the frequencies of light emitted due to transitions between excited states and the first excited state |
| c. | in any transition in a H-atom |
| d. | as a sequence of frequencies with the higher frequencies getting closely packed |
1. (b, c)
2. (a, c)
3. (b, d)
4. (c, d)
