Chromatography is based on the principle of selective _______.

Options

A. Adsorption
B. Absorption
C. Concentration
D. Vaporisation

Answer

**Step-by-Step Solution:**

1. **Understanding Chromatography**: Chromatography is a technique used to separate components of a mixture based on their different interactions with a stationary phase and a mobile phase.

2. **Identifying the Principle**: The key principle behind chromatography is how substances interact with these phases. The interaction can be categorized into different types, such as adsorption and absorption.

3. **Defining Adsorption vs. Absorption**:
- **Adsorption**: This is the process where molecules adhere to the surface of a solid or liquid. In chromatography, the components of the mixture stick to the stationary phase.
- **Absorption**: This involves the incorporation of molecules into the bulk of a solid or liquid.

4. **Applying the Concept**: In chromatography, the components of the mixture are applied to the stationary phase, and as the mobile phase moves through or over it, different components will adhere to the stationary phase to varying degrees.

5. **Conclusion**: Since chromatography relies on the separation of components based on how they adhere to the stationary phase, the correct term to fill in the blank is "adsorption".

**Final Answer**: Chromatography is based on the principle of selective **adsorption**.

---