Notes on Water | Grade 9 > Science > Water | KULLABS.COM

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### Introduction

Water is very essential for life. It is important for human beings, animals, plants and other living organisms to perform their life activities. Water itself supports a large number of living organisms (aquatic plants). No one can live without water. Three by the fourth part of the World is covered by water. The molecular formula of water is H2O.

#### Sources of Water

Those places or parts where there is the origin of water or which produce water are known as sources of water. There are various sources of water on Earth. Some of them are given below,

1. Ocean or sea: 97% of the total water is found in the ocean. It supports a large number of aquatic plants and animals. The water of the ocean is salty so it not useful for day to day activities of the human. But a large number of energy can be produced by using wave and tides of sea water.
2. Ground Water Resources: Those water that are found inside the surface of the earth is known as ground water. They are reserved form of water. They are found in large amount. They are free from dust particles. But they are mixed with germs, minerals, gases etc. They come outside the surface of the earth in the form of small River and rivulets, waterfall, etc.
3. River, lake, ponds and waterfall: River, lake, ponds, waterfall, etc are the various sources of water found on the surface of the water. They are used by various living organisms like animals, plants for various purposes. They are used for drinking, agriculture, industrial purpose, hydroelectric power generation, etc.

#### Properties of Water

Physical Properties

1. Water is found on Earth in the form of solid, liquid and gas. It is found in Mountain in the form of solid i.e. snow and found in a river in the form of liquid and in an atmosphere in the form of vapour.
2. Pure water is tasteless, colorless and orderless.
3. Water is a universal solvent.
4. Water freezes at 0o Celsius and boils at 100o
5. Pure water is a bad conductor of electricity.

Chemical Properties

1. Pure water is a bad conductor of electricity but impure water is a good conductor of electricity. Water can conduct electricity better than other liquid.
2. Lithium, Sodium, Potassium, Calcium etc reacts with water and forms respective hydrogen oxide by displacing the hydrogen of the water.
2Li + 2H2O →2LiOH + H2
2Na + 2H2O → H2
Ca + 2H2O → Ca(OH)2 + H2
3. When acids, base, and salts are dissolved in water, the aqueous solution is formed and they dissociate into their constituent ions.
HCL $$\overset{H_2O}{\rightarrow}$$H+ + CL- (-H2O)
KOH $$\overset{H_2O}{\rightarrow}$$ K+ + OH- (-H2O)
NaCl $$\overset{H_2O}{\rightarrow}$$Na+ + Cl- (-H2O)

Solvent property of water

NaCl (sodium chloride), KNO3 (Potassium nitrate), CaCl2 (calcium chloride) etc like ionic compounds when dissolved in water breaks into ions but water cannot dissolve ionic compounds like AgCl (silver chloride), BaSO4 (barium sulphate), CaF2 (calcium fluoride), etc. It is because there exist a very strong force of attraction between ions which is very difficult to break.

#### Uses of Water

• About 70% of the total water is used in agriculture for food production. To fulfill the foods for growing population, a large amount of water is used for irrigation from river, lakes, waterfall, etc.
• Large amount of water is used in industries and factories for the production of goods and products.
• Water is used for hydroelectric power generation.
• Water is used for daily life activities like for cooking food, drinking, garden, for cleaning etc.
• Water is also used for entertainment like for swimming, rafting, etc.
• It is also used for fish farming and other.
• It is largely used by plants for food production and their living.

• The molecular formula of water is H2O.
• Those places or parts where there is the origin of water or which produce water are known as sources of water.
• 97% of the total water is found in the ocean.
•  Those water that are found inside the surface of the earth is known as ground water.
• Water freezes at 0o Celsius and boils at 100o.
• Pure water is a bad conductor of electricity but impure water is a good conductor of electricity.
• About 70% of the total water is used in agriculture for food production.
• Large amount of water is used in industries and factories for the production of goods and products.
.

### Very Short Questions

Any three physical properties of water are given below,

• It is tasteless, orderless and colourless.
• The boiling point of water is 100 degree celsius.
• The freezing point of water 0 degree celsius.

Any three uses of water are as follows,

• It is used for drinking purpose.
• About 70% of the total water is used in agriculture for food production.
• Water is used for hydroelectric power generation.
• It is largely used by plants for food production and their living.

Any five sources of water are as follows,

• River
• Groundwater
• Ocean or seas
• Lake
• Rainwater

0%

H2O2
H3O
H2O
HO

1%
1%
1%
1%
• ### Water is very essential for

Cooking food
Life
Washing clothes
Cleaning dishes

Land
Water
Forest
Humans
• ### What is the boiling point of water?

100 degree celsius
50 degree celsius
o degree celsius
120 degree celsius
• ### What is the freezing point of water?

5 degree celsius
0 degree celsius
100 degree celsius
2 degree celsius

0%
1%
1%
1%

Lake
Magnetite
River
Ponds

Pure water
Impure water
tap water
Dirty water
• ### Water is found in

All of the given
Gaseous state
Liquid state
Solid state
• ### Which one of the following is not the property of water?

Colourless
Have fixed geometrical shape
Orderless
Tasteless

Stones
Lakes
Rivers
Ponds

## ASK ANY QUESTION ON Water

Forum Time Replies Report

##### avihak

what is surface tension

##### Abhinav Raj Gupta.

1. What are called adhesive property and adhesive force ? 2. What are called cohasive property and cohasive force ?