Question

Which of the following is an example of absorption?

• A. Water on silica gel
• B. Water on calcium chloride
• C. Hydrogen on finely divided nickel
• D. Oxygen on a metal surface

Answer 1

The correct option is B

Water on calcium chloride

Explanation for correct option:

B. Water on calcium chloride

Absorption:

• “In absorption, the substance is uniformly distributed throughout the bulk of the solid.”
• An example of absorption is water vapors are absorbed by anhydrous calcium chloride.

Adsorption:

• “In adsorption, the accumulation of molecular species at the surface rather than in the bulk of a solid or liquid takes place”.
• It is a surface phenomenon.
• An example of adsorption is water vapors are adsorbed by silica gel.

Explanation for incorrect options:

Option A: Water on silica gel is an adsorption phenomenon.

Option C: Hydrogen on finely divided nickel is an adsorption process.

Option D: Oxygen on a metal surface is an adsorption phenomenon.

Hence, the correct option is Option B i.e. Water on calcium chloride.