Which statement is false?

Options

A. Increase in pressure increases the extent of adsorption
B. Increase in temperature may decrease the extent of adsorption
C. The adsorption may be monolayered or multilayered
D. Particle size of the adsorbent will not affect the extent of adsorption

Answer

To determine which statement is false regarding adsorption, we will analyze each statement one by one.

1. **Statement 1: Increase in pressure increases the extent of adsorption.**
- This statement is true. As the pressure of a gas increases, the number of gas molecules striking the surface of the adsorbent also increases. According to Freundlich's isotherm, the extent of adsorption (x/m) is directly proportional to pressure (p). Therefore, an increase in pressure leads to an increase in the extent of adsorption.

2. **Statement 2: Increase in temperature may decrease the extent of adsorption.**
- This statement is also true. Adsorption can be exothermic or endothermic. In exothermic adsorption, increasing the temperature decreases the extent of adsorption because heat is released during the process. Conversely, in endothermic adsorption, increasing the temperature can increase the extent of adsorption. However, since the statement uses "may," it is generally accepted that an increase in temperature can decrease adsorption in exothermic cases.

3. **Statement 3: The adsorption may be monolayered or multilayered.**
- This statement is true. Adsorption can occur in two forms: monolayer adsorption (chemisorption) and multilayer adsorption (physisorption). Monolayer adsorption involves a single layer of adsorbate molecules, while multilayer adsorption involves multiple layers. Therefore, this statement is correct.

4. **Statement 4: The particle size of the adsorbent will not affect the extent of adsorption.**
- This statement is false. The size of the adsorbent particles significantly affects the extent of adsorption. Smaller particles have a larger surface area, which allows for more adsorption sites, while larger particles have less surface area and, therefore, less adsorption capacity. Hence, this statement is incorrect.

### Conclusion:
The false statement is **Statement 4**: "The particle size of the adsorbent will not affect the extent of adsorption."

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