Question

Washing soaps produce scum with hard water and not much foam because hard water contains:
A) Chalk and sulphur.
B) Many dissolve inorganic salt.
C) Many suspended particles.
D) Organic matter.

Answer 1

Hint: As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. As compared with soft water, hard water is water that has high mineral content.

Complete answer:
We cannot imagine our life without water. There are various uses of water. The Most common use of water is for bathing and washing clothes after drinking. The quality of water is important for producing a good amount of foam.
Hard water is responsible for the scum rings seen in bathtubs, as well as the inability of soap to lather.
Hard water has a high concentration of calcium bicarbonate and magnesium bicarbonate in the form of dissolved salts this is called Temporary hardness of water whereas the hardness from chlorides, nitrates and sulphates of calcium and magnesium is called Permanent Hardness.
Hard water is responsible for the scum rings seen in bathtubs, as well as the inability of soap to lather. Due to this washing soaps produce scum with hard water and not much foam.

Hence, option [B] is correct.

Additional Information: By treating water with washing soda, we can remove hardness of water. Insoluble carbonates are formed when washing soda reacts with the sulphide and chloride salts of magnesium and calcium present in hard water. By this process hard water is converted to soft water.

Note: Students generally confuse in two words hard water and heavy water. Hard water means water with a high concentration of dissolved minerals whereas heavy (${D_2}O$ ) water means water containing deuterium instead of normal hydrogen. Both are completely different.