1When soap is stirred into water samples brought from different sources, which beaker gives plenty of foam and which gives only a little? What conclusion can be drawn from the result?
2Well water is put into three test tubes. Soap alone is added to the first, the second is boiled before soap is added, and calcium hydroxide is added to the third before the soap. Which tube gives the most foam? Draw your conclusion.
3What are soft water and hard water? Answer with examples.
4Write the differences between temporary hardness and permanent hardness.
5How does the Clark method remove the hardness of water?
6How is the permanent hardness of water removed by the Permutit method?
7Washing clothes in hard water uses up a lot of soap. Why?
8Rain water is soft but well water is hard. Why?
9A white layer settles at the bottom of a kettle in which water is boiled. What is it and where did it come from?