Question

Why does the skin of your finger shrink, when you wash clothes for a long time?

• A. Soap is hypotonic, so water is moved out of finger by osmosis.
• B. Soap is hypertonic, so water is moved out of finger by osmosis.
• C. Soap is isotonic, so water is moved into finger by osmosis.
• D. Finger skin is very tender.

Answer 1

Answer: (B)

Soap is hypertonic, so water is moved out of finger by osmosis.

• Soap contains a lot of solutes. Hence, when washing clothes, solute concentration is more in soap water than in cells of hand. Due to this, the water molecules present in cells of hand move out in soap solution.
• This is an osmotic process in which the water molecules move from lower solute concentration to higher solute concentration, i.e., from dilute solutions to concentrated solution through a semi-permeable membrane. Soap is a hypertonic solution with high amounts of salts.