Physical adsorption is appeciable at…………….temperature,

Answer

**Step-by-Step Solution:**

1. **Understanding Physical Adsorption**: Physical adsorption, also known as physisorption, involves weak interactions between the adsorbate (the substance being adsorbed) and the adsorbent (the material on which adsorption occurs). These interactions are primarily due to Van der Waals forces.

2. **Nature of Van der Waals Forces**: Van der Waals forces are weak intermolecular forces. The strength of these forces can be affected by temperature. As temperature increases, the kinetic energy of the molecules also increases, which can weaken these interactions.

3. **Effect of Temperature on Adsorption**: When the temperature is increased, the Van der Waals forces become weaker, leading to a decrease in the effectiveness of physical adsorption. This means that at higher temperatures, the adsorption process is less favorable.

4. **Exothermic Nature of Physical Adsorption**: Physical adsorption is an exothermic process, meaning it releases energy when the adsorbate attaches to the adsorbent. According to Le Chatelier's Principle, if a process is exothermic, it is favored at lower temperatures.

5. **Conclusion**: Given the weak nature of Van der Waals forces and the exothermic nature of physical adsorption, it can be concluded that physical adsorption is appreciable at low temperatures.

**Final Answer**: Physical adsorption is appreciable at **low** temperature.

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