Hardness of Water and Treatment

Q. What is Calgon?

1. potassium Phantom metaphosphate
2. sodium penta metaphosphate
3. potassium hexametaphosphate
4. sodium hexametaphosphate

Q. Calculate the mass of residue obtained when $CaC{O}_3$ is strongly heated and $5.6\text{L}C{O}_2$ is produced at STP.

1. $20\text{g}$
2. $18\text{g}$
3. $14\text{g}$
4. $12\text{g}$

Q. The exhausted permutit is generally regenerated by percolating through it a solution of :

1. Sodium chloride
2. Calcium chloride
3. Magnesium chloride
4. Barium chloride

Q.

In comparison to the zeolite process for the removal of permanent hardness, the synthetic resins method is:

1. Less efficient as it exchanges only anions

2. More efficient as it can exchanges only cations

3. Less efficient as the resins cannot be regenerated

4. More efficient as it can exchange both cations as well as anions

Q. What is the degree of hardness of a sample of water containing $24\text{mg}$ of $MgS{O}_4$ (molecular mass $120$) per kg of water?

1. $10\text{ppm}$
2. $15\text{ppm}$
3. $20\text{ppm}$
4. $25\text{ppm}$

Q.

Write the chemical formula for the covalent compound silicon dioxide and mention their molecular weight in brackets after the formula.

Q.

What is the difference between hard water and heavy water? Explain.

Q. What is the weight of $CaO$ required to remove hardness of ${10}^{6}L$ of water containing $1.62gofCa(HC{O}_3{)}_2$ in $1L$ ?
The reaction is ,
$CaO+Ca(HC{O}_3{)}_2\to 2CaC{O}_3+H_{2}O$

1. $9.5\times {10}^{3}g$
2. $3.2\times {10}^{4}g$
3. $2.3\times {10}^{6}g$
4. $5.6\times {10}^{5}g$

Q. Which of the following, do you think are the synthetic resins present in removal of permanent hardness?

1. cation exchange resins only
2. anion exchange resins only
3. both cation exchange resins and anion exchange resins
4. neither cation exchange resins nor anion exchange resins

Q. The temporary hardness of water is due to:

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1. $Ca(HC{O}_3{)}_2$
2. $NaCl$
3. $CaC{l}_2$
4. $N{a}_{2}S{O}_4$

Q. The molecular formula of a commercial resin used for exchanging ions in water softening is $C_8{H}_{7}S{O}_3^{-}N{a}^{+}$ $(Molecularweight=206)$. The maximum uptake of $C{a}^{2+}$ ions by the resin when expressed in mole per gram resin was found to be $\frac{1}{x}$. Find the value of $x$.

Q. $80mL$ of water sample contains $0.162gCa(HC{O}_3{)}_2$ and $0.146gMg(HC{O}_3{)}_2.$ The hardness of water expressed in term of $CaC{O}_3$ is:
(Given : molar mass of $Ca\left(HC{O}_3{)}_{2}andMg\right(HC{O}_3{)}_2$ are 162 and 146 g/mol respectively. )

1. $2.5\times {10}^{3}ppm$
2. $1.5\times {10}^{3}ppm$
3. $6.2\times {10}^{4}ppm$
4. $5\times {10}^{4}ppm$

Q. Which of the following will cause softening of hard water?

1. Passing it through sand.
2. Passing it through cation exchange resin.
3. Passing it through alumina
4. None of the above

Q. The reagent (s) that can be used for softening the temporary hardness of water is (are)

1. ion exchange resins
2. $Ca(OH{)}_2$
3. $N{a}_6{P}_6{O}_{18}$
4. None of the above

Q. Which of the following statements are correct regarding the hardness of water?

1. The temporary hardness of water is due to the presence of bicarbonates of $CaandMg$
2. The temporary hardness of water is due to the presence of sulphates of $NaandMg.$
3. The permanent hardness of water is due to the presence of bicarbonates of $NaandMg.$
4. Permanent hardness is due to presence of soluble chlorides and sulphates of $CaandMg.$

Q. Different water samples A, B, C and D have 150 ppm each of $CaC{l}_2,MgS{O}_4,CaS{O}_{4}andMgC{l}_2$ respectively. The order of degree of hardness of these samples is

1. D > A > B > C
2. A > B > C > D
3. C > B > A > D
4. C > A > D > B

Q. Which of the following is the hard water?

1. Sea water
2. Rain water
3. Distilled water
4. Demineralised water

Q. ${10}^5$ g of a sample of water contained 16.2 g of $Ca(HC{O}_3{)}_2$. It's hardness is

1. 100 ppm
2. 200 ppm
3. 300 ppm
4. 60 ppm

Q.

How is hardness of water caused?

Q. In the Calgon process of softening of water, which of the following is used?

1. Sodium polymetaphosphate
2. Hydrated sodium aluminum
3. Anion exchange resins
4. Silicate cation exchange resins

Q.

The equivalent weight of water in a neutralization reaction between a dibasic acid and triacidic is

Q.

The raw materials used for the preparation of permutit are

1. Soda ash, alumina, silica

2. Lime, silica, caustic soda

3. Zeolite, sand

4. Lime stone, alumina, sand

Q. $9.5\times {10}^{-3}\%MgC{l}_2$ and $1.36\times {10}^{-4}\%CaS{O}_4$ are present in water. What is the measured hardness of water in terms of $CaC{O}_3$?
(Given : molar mass of $MgC{l}_{2}andCaS{O}_4$ are 95 and 136 g/mol respectively. )

1. $20ppm$
2. $56ppm$
3. $200ppm$
4. $101ppm$

Q. Permanent hardness of water can be removed by adding calgon $(NaP{O}_3{)}_6$. This is an example of:

1. Adsorption
2. Exchange of ions
3. Precipitation
4. None of these

Q.

Temporary hardness may be removed from water by adding

1. $CaC{O}_3$

2. $Ca$$(OH{)}_2$

3. $Ca$$S{O}_4$

4. $HCl$

Q. Chemical $A$ is used for water softening to remove temporary hardness. $A$ reacts with sodium carbonate to generate caustic soda. When $C{O}_2$ is bubbled through a solution of $A$, it turns cloudy. What is the chemical formula of $A$?

1. $CaC{O}_3$
2. $CaO$
3. $Ca(OH{)}_2$
4. $Ca(HC{O}_3{)}_2$

Q. In the Calgon process of softening of water, which of the following is used?

1. Sodium polymetaphosphate
2. Hydrated sodium aluminum
3. Silicate cation exchange resins
4. Anion exchange resins

Q. When zeolite, which is hydrated sodium aluminium silicate, is treated with hard water the sodium ions are exchanged with

1. $H^{+}$ ions
2. $C{a}^{2+}$ ions
3. $S{O}_4^{2-}$ ions
4. $M{g}^{2+}$ ions

Q. The exhausted permutit is generally regenerated by percolating through a solution of:

1. Sodium chloride
2. Potassium chloride
3. Calcium chloride
4. Magnesium chloride

Q. $9.5\times {10}^{-3}\%MgC{l}_2$ and $1.36\times {10}^{-4}\%CaS{O}_4$ are present in water. What is the measured hardness of water in terms of $CaC{O}_3$?
(Given : molar mass of $MgC{l}_{2}andCaS{O}_4$ are 95 and 136 g/mol respectively. )

1. $56ppm$
2. $20ppm$
3. $200ppm$
4. $101ppm$