Which experimental observation correctly account for the phenomenon ?

Options

A.
B.
C.
D.

Answer

To solve the question, we need to analyze each of the four experimental observations and determine the phenomenon they are associated with.

### Step-by-Step Solution:

1. **Identify the First Observation: X-ray Spectra**
- X-ray spectra are related to the atomic structure, specifically the number of protons in the nucleus of an atom. The energy levels of X-rays emitted are directly proportional to the atomic number (number of protons).
- **Conclusion**: X-ray spectra are associated with the charge on the nucleus.

2. **Identify the Second Observation: Alpha Particle Scattering**
- The alpha particle scattering experiment, conducted by Rutherford, led to the discovery of the nucleus. It demonstrated that atoms consist of a dense central nucleus surrounded by electrons.
- **Conclusion**: Alpha particle scattering is related to the concept of the nuclear atom.

3. **Identify the Third Observation: Emission Spectra**
- Emission spectra arise when electrons in an atom transition from higher energy levels to lower energy levels, emitting light of specific wavelengths. This is unique for each element, making it a "fingerprint" of the atom.
- **Conclusion**: Emission spectra are associated with quantized electron orbits.

4. **Identify the Fourth Observation: Photoelectric Effect**
- The photoelectric effect demonstrates that light can eject electrons from a material, showing that energy is quantized. It supports the idea that energy is absorbed or emitted in discrete packets (quanta).
- **Conclusion**: The photoelectric effect is related to the quantization of energy.

### Final Associations:
- A (X-ray spectra) is related to 1 (Charge on the nucleus).
- B (Alpha particle scattering) is related to 4 (Nuclear atom).
- C (Emission spectra) is related to 2 (Quantized electron orbit).
- D (Photoelectric effect) is related to 3 (Quantization of energy).