The balmer series for the H-atom can be ob-served

Options

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. none of these

Explanation

To determine when the Balmer series for the hydrogen atom can be observed, we need to understand the transitions of electrons between energy levels in the atom. The Balmer series specifically refers to the spectral lines that are emitted when an electron transitions from a higher energy level to the second energy level (n=2) of the hydrogen atom.

### Step-by-Step Solution:

1. **Understanding Energy Levels**:
- The hydrogen atom has discrete energy levels, denoted by quantum numbers (n=1, n=2, n=3, ...). The lowest energy level is n=1 (ground state), and higher levels are n=2 (first excited state), n=3 (second excited state), and so on.

2. **Defining the Balmer Series**:
- The Balmer series consists of transitions where an electron falls from a higher energy level (n ≥ 3) to the second energy level (n=2). The wavelengths of light emitted during these transitions fall within the visible spectrum.

3. **Identifying Transitions**:
- The transitions that produce the Balmer series are:
- n=3 to n=2
- n=4 to n=2
- n=5 to n=2
- and so forth.
- Each of these transitions corresponds to a specific wavelength of light.

4. **Conditions for Observation**:
- The Balmer series can be observed when the hydrogen atom is in an excited state, meaning that the electrons have absorbed energy and moved to higher energy levels (n ≥ 3). When these electrons return to the n=2 level, they emit light, which can be measured.

5. **Conclusion**:
- Therefore, the Balmer series for the hydrogen atom can be observed when we measure the frequencies of light emitted due to transitions from higher energy states (n ≥ 3) to the first excited state (n=2).

### Final Answer:
The Balmer series for the H atom can be observed when measuring the frequencies of light emitted due to transitions from higher energy levels (n ≥ 3) to the second energy level (n=2).

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