Purification of Water

Q.

How are algal blooms caused?

Q. What are drying agents, desiccating agents, and dehydrating agents? Explain how they work, their nature, uses, and give examples for the same.

Q.

Decantation is a better method of separation than filtration.

1. True
2. False

Q.

State the technique used for separating the following:

Sawdust from water.

Q.

Which of the following is used for the purification of water?

1. UV rays

2. Boiling

3. Filtration

4. Adding chlorine tablet

Q.

You might have observed the preparation of ghee from butter and cream at home. Which method(s) can be used to separate ghee from the residue?

(i) Evaporation

(ii) Decantation

(iii) Filtration

(iv) Churning

Which of the following combination is the correct answer?

1. (i) and (ii)

2. (ii) and (iii)

3. (ii) and (iv)

4. (iv) only

Q.

How can we make river water safe for drinking ?

Q.

Potable water is obtained from river water by the process of

1. Sedimentation only

2. Sedimentation and filtration only

3. Sedimentation, filtration and chlorination only

4. None of these

Q.

What is decantation?

Q. Which filter candle is preferred for water purification?

1. Porcelain candle filter
2. Ceramic candle filter
3. Clay candle filter
4. Polythene candle filter

Q.

7. Arrange the general steps for the purification of drinking water in a sequence.

(1) filtration

(2) chlorination

(3) Sedimentation

(4) addition of chemicals

1. 1 3 2 4

2. 3 1 2 4

3. 3 4 1 2

4. 1 2 4 3

Q.

Alum is used in the purification of river water. Give reasons.

Q.

State what is portable water. Give its qualities or characteristic which make it fit for human consumption.

Q.

The process of pouring out the upper layer of clear liquid without disturbing sediment is called__________.

1. Sedimentation

2. Evaporation

3. Decantation

4. Distillation

Q.

Water obtained from rivers and lakes may contain germs and other impurities. Explain how this water can be made potable.

Q. Which among the following methods were traditionally used for obtaining potable water?

1. Boiling
2. Addition of tulasi leaves
3. Exposing to sunlight
4. Dropping red hot iron balls

Q. Which among the given are traditional methods used to purify water?

1. Sedimentation
2. Filtration
3. Addition of tulasi leaves
4. Adding camphor

Q. The purification of drinking water involves
(i) Chlorination
(ii) Filtration
(iii) Loading
(iv) Sedimentation
Choose the correct order of these processes.

1. i, ii, iii, iv
2. ii, iv, iii, i
3. iv, iii, ii, i
4. iv, ii, iii, i

Q. Which of the following is not a feature of potable water?

1. It must be clean, colourless and odourless.
2. It must be free from bacteria.
3. It must have excessive sodium, calcium, and magnesium as they give a special taste.
4. It must contain dissolved oxygen and carbon dioxide.

Q. What do you understand by potable water? Explain any one method to make water from other sources potable.

Q. A mixture of sand and water can be separated by the method:

1. filtration
2. evaporation
3. sedimentation followed by decantation
4. sublimation

Q.

Potable water should contain _________________________.

Q. Deactivated filters in activated carbon method for defluoridation can be activated by:

1. defluoran-1 and defluoran-2
2. lime, bleaching powder and alum
3. $4\%$ $NaOH$ and $1\%$ $H_{3}P{O}_4$ solution
4. $4\%$ $NaCl$ and $5\%$ $H_{2}S{O}_4$ solution

Q. When water is purified by adding chlorine it is called _____________.

1. Chlorification
2. Chlorinization
3. Chlorination
4. Chlorine filter

Q.

36. Arrange the process in sequence for the purification of drinking water

(1) lime feeder, alum feeder

(2) filtration

(3) mechanical mixing

(4) chlorination

1. 1324

2. 1243

3. 2345

4. 2341

Q. Sewage waste contains mainly water.

1. True
2. False