Q.Action of soap is due to emulsification and micelle formation. Comment.

Step 1 – Structure of soap. Soap is the sodium/potassium salt of a higher fatty acid, e.g. sodium stearate $C_{17}H_{35}COO^{-}Na^{+}$. It is an associated colloid: each molecule has a long non-polar (hydrophobic) hydrocarbon tail and a polar (hydrophilic) carboxylate head $-COO^{-}$.

Step 2 – Micelle formation. Above the critical micelle concentration (CMC), soap molecules aggregate into micelles — spherical clusters with the hydrocarbon tails pointing inward (away from water) and the ionic heads on the outside facing water.

Step 3 – Cleansing (emulsification of grease). Dirt is generally held to fabric by grease/oil, which is insoluble in water. When soap solution is applied:

• the hydrophobic tails penetrate/dissolve into the grease droplet, while
• the hydrophilic heads remain in the water. …

Use the dual (hydrophobic tail / hydrophilic head) structure of soap: it forms micelles and emulsifies grea …

• Not mentioning the dual (polar head/non-polar tail) structure that drives micelle formation.
• Saying soap chemically dissolves grease rather than emulsifying it. …