Question

Absorption of ink by blotting paper involves

• A. Siphon action
• B. Diffusion through the blotting
• C. Capillary action
• D. Viscosity of ink

Hint:

Blotting paper has tiny gaps between fibers that act like narrow tubes pulling liquid in.

Answer 1

The Correct Option is C

Blotting paper is made of loosely packed cellulose fibers. This structure creates a network of very fine, narrow gaps between the fibers, and these gaps behave like tiny capillary tubes.

When ink touches the paper, the adhesive force between the ink molecules and the paper fibers is stronger than the cohesive force between the ink molecules themselves. This imbalance, along with the surface tension of the ink, pulls the liquid into the narrow gaps and spreads it through the paper. This process is called capillary action.

Siphon action needs a bent tube and a height difference to keep liquid flowing under atmospheric pressure. There is no such tube or setup in blotting paper, so option A is wrong.

Diffusion is the slow mixing of particles from a region of high concentration to low concentration. It does not explain the quick pulling of ink into narrow channels, so option B is wrong.

Viscosity is the internal resistance of a fluid to flow. A higher viscosity would actually slow down absorption, not cause it, so option D is wrong.

The correct answer is capillary action.