Whenever a hydrogen atom emits a photon in the Balmer series .

Options

A. it need not emit any more photon
B. it may emit another photon in the Paschen series
C. it may emit another photon in the Lyman series
D. it may emit another photon in the Balmer series

Explanation

To solve the question regarding the emission of a photon by a hydrogen atom in the Balmer series, we need to analyze the transitions of the electron in the hydrogen atom.

### Step-by-Step Solution:

1. **Understanding the Balmer Series**:
- The Balmer series corresponds to electronic transitions in a hydrogen atom where the electron falls to the n=2 energy level from higher energy levels (n=3, n=4, etc.). When this transition occurs, a photon is emitted.

2. **Identifying the Initial State**:
- When a hydrogen atom emits a photon in the Balmer series, the electron must be transitioning from a higher energy level (n > 2) to the n=2 level.

3. **Possible Subsequent Transitions**:
- After the emission of a photon in the Balmer series, the electron can be in the n=2 state. From here, it can either:
- Remain in the n=2 state (no further emission).
- Transition to a lower energy level (n=1) and emit a photon in the Lyman series.
- Absorb energy and move to a higher energy level (which would not result in emission).

4. **Evaluating the Options**:
- **Option 1**: "It need not emit any more photon" - This is possible if the electron remains in the n=2 state.
- **Option 2**: "It may emit another photon in the Paschen series" - This is incorrect because the Paschen series involves transitions to n=3, which cannot occur from n=2 without absorbing energy.
- **Option 3**: "It may emit another photon in the Lyman series" - This is correct because the electron can transition from n=2 to n=1, emitting a photon in the Lyman series.
- **Option 4**: "It may emit another photon in the Balmer series" - This is incorrect as the Balmer series involves transitions to n=2 from higher levels, not from n=2 to another n=2 state.

5. **Conclusion**:
- The correct answer is Option 3: "It may emit another photon in the Lyman series".