The correct option is (c) 2 and 3 only.
Explanation
The Tyndall effect is an optical phenomenon where a beam of light is scattered by particles suspended in a medium. This scattering makes the path of the light beam visible. It is primarily determined by the size of the particles in relation to the wavelength of the light.
Statement-wise Analysis:
- Statement 1 is Incorrect: The Tyndall effect requires the presence of suspended particles to scatter light. A vacuum is a space devoid of matter; therefore, there are no particles to interact with the light, and the effect cannot be observed.
- Statement 2 is Correct: The phenomenon is caused by the scattering of light by particles. When a beam of light strikes particles that are large enough (roughly 1 to 1000 nanometers), the light is deflected in different directions, illuminating the path of the beam.
- Statement 3 is Correct: The Tyndall effect is a defining characteristic of colloidal solutions (e.g., milk, mist). In contrast, the particles in a true solution are too small to scatter light significantly, so the path of light remains invisible.
Key Takeaway:
The Tyndall effect serves as a practical test to distinguish between a true solution (no scattering) and a colloidal solution (visible scattering path).