Advertisements
Advertisements
प्रश्न
How is water purified on a large scale at water works ? Explain with the help of a labelled diagram. Name the substance which is added to kill germs in the drinking water supply ?
Advertisements
उत्तर
Various processes are used to purify water on large scale at water works. The source of water for cities is nearby a river or a lake. This water generally contains suspended particles, dissolved impurities and germs. In order to supply this water to homes, it has to be purified. Following steps are involved to purify water at water works:
- In water works, methods like sedimentation, decantation, loading, filtration and chlorination etc., are used to remove undesirable materials from water.
- The source of water supply in a city is either a nearby river or lake (reservoir). From there, it is pumped to a 'sedimentation tank'.
- It is kept here for some time to allow the insoluble substances present in water to settle down at the bottom of the tank.
- It is then sent to a 'loading tank', where some alum is added to water.
- Suspended clay particles in water get loaded here with alum particles. After becoming heavy, they settle down at the bottom of the tank. Thus, the process of loading removes the suspended clay particles from water.
- It is then passed through a 'filtration tank' having three layers, i.e., fine sand layer on the top, coarse sand layer in the middle and gravel layer at the bottom .
- These layers act as filters and remove small suspended particles of the water.
- Water is then passed into a chlorination tank. Here, chlorine is added to water to kill the germs present in it.
- Now the clean and disinfected water is pumped to high storage tanks by pumping stations. From these high storage tanks, water is supplied to homes and factories through a network of big and small pipes.
Figure 65. Supply of drinking water in a city.
Chlorine is added to water to kill germs in the drinking water supply.
APPEARS IN
संबंधित प्रश्न
Solids have definite shape and definite volume.
Give one difference between atoms and molecules.
Fill in the following blanks with suitable words :
Brass is an alloy which is considered a ..............
Out of a colloid, solution and a suspension :
which one has the largest particles ?
What is a suspension ? Give two examples of suspensions.
100 mL of water at room temperature of 25°C is taken in a beaker and a little of solid S is dissolved in it by stirring to obtain a solution X. More and more of solid S is added to the solution with constant stirring, while keeping the temperature of solution constant at 30°C. After some time it is observed that no more solid dissolves in water and at the same time some solid is also left undissolved at the bottom of the beaker.
- The contents of beaker are filtered through a filter paper to obtain solution Y in the form of a filtrate.
- What name is given to solutions like X ?
- What name is given to solutions like Y ?
- What will you observe if the solution Y at 30°C is cooled down to 10°C by keeping the beaker in crushed ice ? Why ?
- What term is used to denote the amount of solid dissolved in 100 grams of water in a solution lie Y ?
Name the source from which nitrogen and oxygen are obtained on a large scale.
Which method is better for recovering sugar from sugar solution : evaporation or crystallisation ? Give reason
for your answer.
The correct increasing order of the boiling points of liquid oxygen, liquid argon and liquid nitrogen present in liquid air is :
The liquid air has three components X, Y and Z whose boiling points are : –186°C, –183°C and –196°C,
respectively. When liquid air is fed into a tall fractional distillation column from near its bottom and warmed
up slowly :
(a) Which component will be collected from near the bottom of the fraction distillation column ? Why ?
(b) Which component will be collected from the top part of the fractional distillation column ? Why ?
(c) Which component will be collected from the middle part of the fractional distillation column ? Why ?
(d) What could the component X, Y and Z be ?
A solid mixture contains four constituents P, Q, R and S. P consists of tiny grains and it is mixed with
cement for plastering the walls. Q is a white solid which is recovered on a large scale from sea water by the
process of evaporation. R is in the form of tiny particles of a material whose corrosion is called rusting. And
S is a white solid which is used in making ordinary dry cells.
- What could P, Q, R and S be ?
- How would you separate a mixture containing P, Q, R and S ?
Match the physical quantities given in column A to their S I units given in column B:
| (A) | (B) | ||
| (a) | Pressure | (i) | cubic metre |
| (b) | Temperature | (ii) | kilogram |
| (c) | Density | (iii) | pascal |
| (d) | Mass | (iv) | kelvin |
| (e) | Volume | (v) | kilogram per cubic metre |
The non S I and S I units of some physical quantities are given in column A and column B respectively. Match the units belonging to the same physical quantity:
| (A) | (B) | ||
| (a) | degree celsius | (i) | kilogram |
| (b) | centimetre | (ii) | pascal |
| (c) | gram per centimetre cube | (iii) | metre |
| (d) | bar | (iv) | kelvin |
| (e) | milligram | (v) | kilogram per metre cube |
______ is so hard that it can scratch glass.
______ is used for industrial refrigeration and transporting frozen food.
Give an example of a molecule.
Define the term matter.
Define the term matter.
Define the term matter.
