Question

Hardness of water is due to presence of?.

Answer 1

Hint: Hard water is described as water that contains a significant amount of dissolved minerals (like calcium and magnesium). Soft water is filtered water in which sodium is the only ion. Rainwater is naturally soft when it falls.

Complete answer:
Dissolved calcium and, to a lesser degree, magnesium trigger hardness in water. It's normally expressed in terms of calcium carbonate equivalents. Hardness levels above 200 mg/l, depending on pH and alkalinity, may cause scale deposition, particularly when heated.
When natural waters flow over calcium or magnesium compounds in the ground or rocks, hard water is created. Chalk and limestone, for example, are mostly calcium carbonate (\[CaC{O_3}\]) with some magnesium carbonate (\[MgC{O_3}\]), which are naturally acidified by carbon dioxide gas absorbed from the atmosphere.
Water is graded as soft if it contains less than \[60\] \[mg/L\](milligrams per litre) of calcium carbonate, moderately hard if it contains more than \[120{\text{ }}mg/L\],hard if it contains more than \[180{\text{ }}mg/L\],and very hard if it contains more than \[180{\text{ }}mg/L\].
The lower the toxicity of other metals to marine organisms, the harder the water is. Some metal ions form insoluble precipitates and drop out of solution in hard water, making them unable to be taken in by organisms. Large quantities of hardness are undesirable for a variety of reasons, mostly economic and aesthetic.

Note:
Researchers discovered that every one-unit increase in water hardness resulted in a \[1\% \] reduction in the risk of heart attack. In particular, each \[3\% \] rise in fluoride in household drinking water was linked to a \[3\% \] reduction in the risk of heart attack.