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प्रश्न
Which of the following ions will cause hardness in water sample?
विकल्प
\[\ce{Ca^{2+}}\]
\[\ce{Na+}\]
\[\ce{Cl-}\]
\[\ce{K+}\]
उत्तर
\[\ce{Ca^{2+}}\]
Explanation:
\[\ce{Ca++}\] ions in the form of \[\ce{Ca(HCO3)2}\] or \[\ce{CaCl2}\] or \[\ce{CaSO4}\] cause hardness in water, i.e., soluble salts of calcium can cause hardness in water.
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संबंधित प्रश्न
What is meant by ‘demineralised’?
Is demineralised or distilled water useful for drinking purposes? If not, how can it be made useful?
Which of the following compounds is used for water softening?
Hardness of water may be temporary or permanent. Permanent hardness is due to the presence of:
(i) Chlorides of \[\ce{Ca}\] and \[\ce{Mg}\] in water.
(ii) Sulphates of \[\ce{Ca}\] and \[\ce{Mg}\] in water.
(iii) Hydrogen carbonates of \[\ce{Ca}\] and \[\ce{Mg}\] in water.
(iv) Carbonates of alkali metals in water.
Complete the following equations:
\[\ce{CO (g) + 2H2 (g) ->[Cobalt][Catalyst]}\]
Discuss briefly de-mineralisation of water by ion exchange resin.
Match the items in Column I with the relevant item in Column II.
| Column I | Column II |
| (i) Hydrogen peroxide is used as a | (a) zeolite |
| (ii) Used in Calgon method | (b) perhydrol |
| (iii) Permanent hardness of hard water is removed by | (c) sodium hexametaphosphate |
| (d) propellant |
Assertion (A): Permanent hardness of water is removed by treatment with washing soda.
Reason (R): Washing soda reacts with soluble magnesium and calcium sulphate to form insoluble carbonates.
Which one of the following methods is most suitable for preparing deionized water?
100 ml of a water sample contains 0.81 g of calcium bicarbonate and 0.73 g of magnesium bicarbonate. The hardness of this water sample expressed in terms of equivalent of CaCO3 is ______.
[Molar mass of calcium bicarbonate is 162 g mol-1 and magnesium bicarbonate is 146 g mol-1)
