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Hardness of Water:Causes, Types and Treatments

Which of the ...

Question

Which of the following substances cause permanent hardness of water?

A

C a C l_{2}

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B

C a {(H C O_{3})}_{2}

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C

C a C O_{3}

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D

All of the above

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Solution

The correct option is A $C a C l_{2}$
Permanent hardness is caused by dissolved chloride, sulfate, and nitrates of Calcium & magnesium (which are not removed by boiling) and temporary hardness is caused by dissolved calcium hydrogen carbonate (which is removed by boiling).

Hence, the correct option is $A.$

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Similar questions

Q. Permanent hardness is due to

S O_{4}^{2 -}

C l^{-}

C a^{2 +}

M g^{2 +}

and is removed by the addition of

N a_{2} C O_{3}

.

C a S O_{4} + N a_{2} C O_{3} ⟶ C a C O_{3} + N a_{2} S O_{4}

C a C l_{2} + N a_{2} C O_{3} ⟶ C a C O_{3} + 2 N a C l

100

C a C O_{3}

N a_{2} C O_{3}

required to soften

10

L of hard water is :

Q. Permanent hardness is due to

C l^{⊝}

S O_{4}^{2 -}

M g^{2 +}

C a^{2 +}

and is removed by adding

N a_{2} C O_{3}

C a S O_{4} + N a_{2} C O_{3} \to C a C O_{3} + N a_{2} S O_{4}

C a C l_{2} + N a_{2} C O_{3} \to C a C O_{3} + 2 N a C l

Which of the following statements is/are correct?

10

L of hard water with temporary hardness of

[C a (H C O_{3})_{2}]

0.56

g of lime. The reaction follows as:

C a (H C O_{3})_{2} + C a O ⟶ 2 C a C O_{3} + H_{2} O

.
Temporary hardness in terms of ppm of

C a C O_{3}

Q. Mention the ions which cause temporary and permanent hardness of water

C a S O_{4}

causes permanent hardness in water. It can be removed by precipitating it as

C a C O_{3}

N a_{2} C O_{3}

. If the amount of

N a_{2} C O_{3}

required to soften 100 L of hard water, which is 200 ppm

C a C O_{3}

x

g, then value of

x

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