Permutit is:

1. hydrated sodium aluminium silicate

2. sodium hexa meta-phosphate

3. sodium silicate

4. sodium meta-aluminate

Which is used to determine hardness of water volumetrically ?

1. H₂C₂O₄

2. Na₂S₂O₃

3.Sod. citrate

4. Di sodium salt of EDTA

Both temporary and permanent hardness are removed on boiling water with:

1. Ca(OH)₂

2. Na₂CO₃

3. CaCO₃

4. CaO

When zeolites (hydrated sodium aluminum silicate) is treated with hard water, the sodium ions are exchanged with:

1. H⁺ ion

2. Ca²⁺ ion

3. ${\mathrm{SO}}_4^{2-}$ ion

4. OH^- ion

Temporary hardness is caused due to the presence of:

1. CaSO₄

2. CaCl₂

3. CaCO₃

4. Ca(HCO₃)₂

A 1000 g aqueous solution of CaCO₃ contains 10 g of calcium carbonate. The hardness of the solution is:

1. 10 ppm

2. 100 pm

3. 1000 ppm

4. 10000 ppm

 Hardness of water cannot be removed by -

1. Clark's method

2. Adding washing soda

3. Calgon process

4. Filtration

Polyphosphates are used as water softening agents because they –

(1) form soluble complexes with anionic species

(2) precipitate anionic species

(3) form soluble complexes with cationic species

(4) precipitate cationic species

Permanent hardness of water can be removed, by adding –

(1) Soda lime

(2) Sodium bicarbonate

(3) Washing soda

(4) Sodium chloride

Hardness of water is due to presence of salts of –

(1) ${\mathrm{Na}}^{+} \mathrm{and} {\mathrm{K}}^{+}$                                  

(2) ${\mathrm{Ca}}^{2+} \mathrm{and} {\mathrm{Mg}}^{2+}$

(3) ${\mathrm{Ca}}^{2+} \mathrm{and} {\mathrm{K}}^{+}$                                

(4) ${\mathrm{Ca}}^{2+} \mathrm{and} {\mathrm{Na}}^{+}$