In which transition, one quantum of energy is emitted

Options

A. `n_(2)=4 to n_(1)=2`
B. `n_(1)=3 to n_(1)=1`
C. `n_(2)=2 to n_(1)=1`
D. All of these

Answer

To determine in which transition one quantum of energy is emitted, we need to understand the behavior of electrons in an atom when they transition between energy levels.

### Step-by-Step Solution:

1. **Understand Energy Levels**: Electrons exist in specific energy levels (or shells) around the nucleus of an atom. These energy levels are quantized, meaning electrons can only occupy certain discrete levels.

2. **Identify Energy Transitions**: When an electron transitions between these energy levels, it can either absorb or emit energy:
- **Energy Absorption**: If an electron moves from a lower energy level (n1) to a higher energy level (n2), it absorbs energy from an external source.
- **Energy Emission**: If an electron moves from a higher energy level (n2) to a lower energy level (n1), it emits energy in the form of a quantum (photon).

3. **Determine the Transition**: For the question, we need to find a transition where energy is emitted. This occurs when the electron moves from a higher energy level to a lower energy level.

4. **Example of Energy Transition**: Let's consider an example where an electron transitions from n2 = 4 to n1 = 2. Here, the electron is moving from a higher energy level (n=4) to a lower energy level (n=2). In this case, energy is emitted.

5. **Conclusion**: The transition where one quantum of energy is emitted occurs when an electron jumps from a higher energy level to a lower energy level.

### Final Answer:
The transition in which one quantum of energy is emitted is when an electron moves from a higher energy level (n2) to a lower energy level (n1).

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