The correct answer is option 3. Key Points - Soaps are molecules in which the two ends have differing properties. - One is hydrophilic, which dissolves in water, while the other end is hydrophobic, which dissolves in hydrocarbons. - Soap in the form of a micelle is able to clean since the oily dirt gets collected in the center of the micelle. - The micelles stay in solution as a colloid and don't come together to precipitate because of ion-ion repulsion. - The soap micelles are large enough to scatter light and hence a soap solution appears cloudy. - Soap is a mixture of sodium salts of various naturally occurring fatty acids. - Soap foam is formed with difficulty and an insoluble substance (scum) remains after washing with water. - This is caused by the reaction of soap with the calcium and magnesium salts, which cause the hardness of the water.