Which of the following phenomena support the wave theory of light?
1. Scattering
2.Interference
3. Diffraction
4. Velocity of light in a denser medium is less than the velocity of light in the rare medium

Options

A. 1, 2 and 3
B. 1, 2 and 4
C. 2, 3 and 4
D. 1, 3 and 4

Explanation

To determine which phenomena support the wave theory of light, we will analyze each option provided in the question:

1. **Scattering**: Scattering refers to the process where light is redirected in various directions after interacting with particles. This phenomenon is primarily explained by the particle theory of light, as it involves the interaction of photons with matter. Therefore, scattering does not support the wave theory of light.

2. **Interference**: Interference occurs when two or more waves overlap and combine to form a new wave pattern. This phenomenon is a clear demonstration of the wave nature of light, as it results in the formation of bright and dark fringes due to constructive and destructive interference. Thus, interference supports the wave theory of light.

3. **Diffraction**: Diffraction is the bending of light waves around obstacles and the spreading of waves when they pass through narrow openings. This behavior is characteristic of waves and cannot be adequately explained by the particle theory. Hence, diffraction supports the wave theory of light.

4. **Velocity of light in a denser medium is less than the velocity of light in a rarer medium**: According to the wave theory, light travels slower in denser media compared to rarer media due to the interaction of light waves with the medium. This phenomenon aligns with the wave theory of light, as it explains the change in speed based on the medium's properties.

Based on the analysis above, the phenomena that support the wave theory of light are:

- Interference (Option 2)
- Diffraction (Option 3)
- Velocity of light in a denser medium being less than in a rarer medium (Option 4)

Thus, the correct answer is options 2, 3, and 4.

### Final Answer:
The phenomena that support the wave theory of light are:
- Interference (2)
- Diffraction (3)
- Velocity of light in a denser medium is less than in a rarer medium (4)