Why does soap produce less lather with hard water while washing clothes?
Answer and explanation
Correct answer: Hard water contains calcium and magnesium salts
Hard water contains dissolved calcium and magnesium ions, commonly supplied by their salts. Soap contains fatty-acid ions that react with Ca²⁺ and Mg²⁺ to form insoluble scum. These precipitates consume soap before it can form lather, so option A identifies the cause. Hard water does contain ions, is not an acidic gas, and soap is not completely unable to dissolve. Washing soda can soften water by removing these ions.
Frequently asked questions
What is the correct answer to this question?
Hard water contains calcium and magnesium salts
Why is this the correct answer?
Hard water contains dissolved calcium and magnesium ions, commonly supplied by their salts. Soap contains fatty-acid ions that react with Ca²⁺ and Mg²⁺ to form insoluble scum. These precipitates consume soap before it can form lather, so option A identifies the cause. Hard water does contain ions, is not an acidic gas, and soap is not completely unable to dissolve. Washing soda can soften water by removing these ions.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
