Question

salt used to remove permanent hardness of water​

Answer 1

Water softening is achieved either by adding chemicals that form insoluble precipitates or by ion exchange. On a small scale, chemicals used for softening include ammonia, borax, calcium hydroxide (slaked lime), or trisodium phosphate, usually in conjunction with sodium carbonate (soda ash).

Answer 2

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Explanation:

Detergent is the sodium salt of a long chain benzene sulphonic acid (or the sodium salt of a long chain of alkyl hydrogen sulfate), which repels the Ca2+ or Mg2+ ions. When added to water, they don't produce insoluble precipitates, and therefore dissolve easily in the hard water