Correct Option :
Option 4: I, II, III and IV
Hard water contains dissolved mineral salts, primarily calcium and magnesium ions. These ions can interfere with various processes, making hard water unsuitable for multiple applications.
- Drinking: While generally not harmful, excessive mineral content in hard water can alter its taste and may contribute to mineral deposits in the body over long periods, though this is less of a primary concern than other issues.
- Washing clothes with soap: The calcium and magnesium ions in hard water react with soap to form insoluble precipitates (scum). This reduces the lathering ability of soap, requiring more soap for effective cleaning, and can leave deposits on clothes, making them appear dull or stiff.
- Use in boilers: When hard water is heated in boilers, the dissolved minerals precipitate out, forming scale (limescale) on the inner surfaces of pipes and heating elements. This scale reduces heat transfer efficiency, increases fuel consumption, and can lead to blockages and damage to the boiler system.
- Irrigating crops: High concentrations of certain minerals in hard water, particularly sodium, can accumulate in the soil over time. This can negatively impact soil structure, reduce water infiltration, and create saline conditions that are detrimental to crop growth and yield.
Incorrect Options:
Options 1, 2, and 3 are incorrect because hard water is unsuitable for all the listed applications (drinking, washing clothes with soap, use in boilers, and irrigating crops) due to the presence of dissolved mineral salts which cause various undesirable effects.