Question

What do you mean by the degree of hardness?

Answer 1

Hint : In order to answer the question we should first get some idea about the hard and soft water. Hard water is defined as water that contains a significant amount of dissolved minerals (like calcium and magnesium). Soft water, on the other hand, is treated water in which the sole ion present is sodium.

Complete Step By Step Answer:
Rainwater is naturally gentle as it falls. Water, on the other hand, gathers up minerals like chalk, lime, and predominantly calcium and magnesium as it travels through the ground and into our waterways, resulting in hard water. Hard water is sometimes favoured as a drinking water since it includes vital minerals. Not only for the health benefits, but also because of the flavour. Soft water, on the other hand, has a salty flavour and isn't always safe to drink.
A unit of water hardness, specifically general hardness, is degrees of general hardness $\left( {dGH{\text{ }}or{\text{ }}^\circ GH} \right).$ The concentration of divalent metal ions such as calcium $\left( {C{a^{2 + }}} \right)$ and magnesium $\left( {M{g^{2 + }}} \right)$ per volume of water is referred to as general hardness. $10{\text{ }}milligrammes{\text{ }}\left( {mg} \right)$ of calcium oxide ( $CaO$ ) per litre of water is defined as $1{\text{ }}dGH.{\text{ }}1{\text{ }}dGH$ is equal to $0.17832$ mmol per litre of elemental calcium and/or magnesium ions, because $CaO$ has a molar mass of $56.08{\text{ }}g/mol.$

Note :
In water testing, paper strips frequently assess hardness in parts per million (ppm), where one part per million is defined as one milligramme of calcium carbonate $\left( {CaC{O_3}} \right)$ per litre of water. As a result, $1{\text{ }}dGH$ equals $10{\text{ }}ppm{\text{ }}CaO$ but $17.848{\text{ }}ppm{\text{ }}CaC{O_3}$ , which has a molar mass of $100.09{\text{ }}g/mol$ and a molar mass of $100.09{\text{ }}g/mol.$