Principle of paper chromatography

Paper chromatography is essentially a partition chromatography.

• The paper acts mainly as a support.
• Water retained in the pores/cellulose fibers of the paper acts as the stationary phase.
• The solvent moving upward/downward acts as the mobile phase.

Evaluate each option

Option A: Water present in the mobile phase gets absorbed by the paper which then forms the stationary phase.

• This is not the standard description.
• In paper chromatography, the stationary phase is the water already held in the pores of the paper, not simply the mobile phase water getting absorbed during movement.
• Hence, A is incorrect.

Option B: Water present in the pores of the paper forms the stationary phase.

• This is the correct statement.
• The cellulose paper holds water in its pores, and this retained water behaves as the stationary phase.
• Hence, B is correct.

Option C: Paper sheet forms the stationary phase.

• The paper itself is only a support medium.
• The actual stationary phase is the water adsorbed/held in the paper pores.
• Hence, C is incorrect.

Option D: Paper and water present in its pores together form the stationary phase.

• In standard JEE chemistry, the stationary phase is specifically taken as water present in the pores of the paper.
• Paper is considered the support, not the stationary phase itself.
• Hence, D is incorrect.

Final answer

The correct option is: $\boxed{\text{B}}$

Comparison with stored correct answer

• Stored correct answer: B
• Derived answer: B
• Therefore, they agree.