Removal of Hardness in Water

Q.

What is the cause of hardness of water?

Q.

What happens when the temporary hard water is boiled? Give chemical equation also.

Q.

State the reasons for hardness in water

Q.

What is meant by the temporary and permanent hardness of water and how is it caused?

Q. Washing soda is used to soften hard water.

1. True
2. False

Q.

Give reasons for the following

When hardness in temporary hard water can be removed by boiling but the hardness of permanent hard water cannot.

Q.

How can temporary hardness of water be removed? Give proper chemical equation in support of you answer.

Q.

Permanent hardness of water can be removed by adding ____.

1. Sodium carbonate

2. Sodium bicarbonate

3. Calcium sulphate

4. Sodium chloride

Q.

Which salt does not cause hardness in water?

1. Calcium

2. Sodium

3. Magnesium

4. Both 1 & 3

Q.

A water sample contains magnesium bicarbonates. It does not lather with soap. How can we make the water sample useful for cleaning clothes?

1. Boiling

2. Cooling

3. By addition of Sodium

4. By addition of water

Q.

Hardness of water is due to

1. Chloride of calcium

2. Bicarbonate of magnesium

3. Sulphate of aluminium

4. Both (A) & (B)

Q.

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 water-soluble compounds.

1. (A) and (R) both are correct and (R) is the correct explanation of (A).

2. (A) and (R) both are correct but (R) is not the correct explanation of (A).

3. (A) is correct but (R) is not correct.

4. (A) is not correct but (R) is correct.

Q.

Explain how temporary hardness of water can be removed by boiling ?

Q. Choose the correct pair:

1. Spring water
2. Soft water
3. Addition of $N{a}_{2}C{O}_3$
4. Permanent hardness
5. Boiling
6. Temporary hardness

Q. The temporary hardness of water can be removed by:

1. Addition of potassium permagenate

2. Boiling

3. Cooling

4. Addition of chlorine

Q.

Which of the following is not true?

1. The hardness of water depends on its behaviour towards soap.

2. The temporary hardness is due to the presence of calcium and magnesium bicarbonates.

3. Permanent hardness is due to the presence of soluble calcium and magnesium sulphates, chlorides and nitrates.

4. Permanent hardness can be removed by boiling the water.

Q.

Permanent hardness of water can be removed by:

1. Boiling

2. Addition of washing soda

3. Addition of potassium permanganate

4. Addition of slaked lime