(a) hydrated sodium aluminium silicate
(b) sodium hexa meta-phosphate
(c) sodium silicate
(d) sodium meta-aluminate
(a) Permutit are complex inorganic salts like sodium alumino silicate
When zeolites, (hydrated sodium aluminium silicate) is treated with hard water, the sodium ions are exchanged with:
(a) H+ ion
(b) Ca2+ ion
(d) OH- ion
Temporary hardness is caused due to the presence of:
(d) Bicarbonates of Ca and Mg are responsible for temporary hardness.
1000 g aqueous solution of CaCO3 contains 10g of calcium carbonate. Hardness of the solution is:
(a) 10 ppm
(b) 100 pm
(c) 1000 ppm
(d) 10000 ppm
(d) Hardness is expressed in g of CaCO3 present in 106g of H2O.
Which method cannot be used to remove hardness of water ?
(a) Clark's method
(b) By adding washing soda
(c) Calgon process
(d) The ions responsible for hard water are soluble in water.
Which salt does not cause hardness of water ?
(4) MgCO3 does not cause hardness of water.
Chemical A is used for water softening to remove temporary hardness. A reacts with sodium carbonate to generate caustic soda. When is bubbled through a solution of A, it turns cloudy. What is the chemical formula of A
(C). is used for the softening of temporary hard water.
Polyphosphates are used as water softening agents because they –
(A) form soluble complexes with anionic species
(B) precipitate anionic species
(C) form soluble complexes with cationic species
(D) precipitate cationic species
(C). Sodium hexametaphosphatea polyphosphate, combines with cations to
form soluble complexes.
Permanent hardness of water can be removed, by adding –
(C) Washing soda
(D) Sodium chloride
(C). Washing soda removes both the temporary and permanent hardness by converting soluble
calcium and magnesium compounds into insoluble carbonates.
Hardness of water is due to presence of salts of –
(B). Hardness of water is due to the presence of bicarbonates, chlorides and sulphates of Ca and
Mg on it. These ions react with the anions of fatty acids present in soaps to
form curdy white precipitates. As a result, hard water does not produce lather with soap