1. A sample of water with which soap does not form good lather is called hard water.

    A sample of water with which soap does not form good lather is called hard water.

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  2. Foam produced by soap in water is called lather.

    Foam produced by soap in water is called lather.

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  3. The organic part of soap (C₁₇H₃₅ COO⁻) combines with the Ca²⁺ ion of hard water and forms insoluble precipitate called scum. Thus, a large portion of soap is wasted in hard water and washing is not effective.

    The organic part of soap (C₁₇H₃₅ COO⁻) combines with the Ca²⁺ ion of hard water and forms insoluble precipitate called scum. Thus, a large portion of soap is wasted in hard water and washing is not effective.

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