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Ananthapur, Kadapa and Kurnool are drought-prone districts in AP.

• If there is no rain for a long period, it may cause drought. 
• It creates a water shortage that damage crops, livestock and the environment. 
• To control drought, we have to follow the given activities. 
• We should control the emission of gases which causes pollution. 
• Control deforestation and encourage forestation. 
• We should promote water conservation techniques. 
• Wastewater treatment should be implemented. We should follow wastewater recycling, desert landscaping. 
• We should use water judiciously to prevent water scarcity. 
• We should follow the water conservation methods.

i) No. a Bucket is not a measure of the volume of water used.

ii) We measure the volume of water by using the shape of the vessel containing the water.

iii) Yes. Water and other liquids have a specific unit to measure the volume in litres.

The student is advised to collect the information from his/her grandparents and their experiences about the drought.

If there is no rain for a long period, it may cause drought.

Oxygen and hydrogen

Chemical composition = H₂ and O₂ proportion 2:1

Molecular formula = H₂O

(d) Precipitation

• Our primary needs are air, water and food.
• We need water for many activities in our daily life. 
• Water is a precious gift of nature. 
• We can’t live a single day without water. 
• In some areas, people are suffering from a lack of drinking water. 
• Some areas are slowly becoming deserts due to lack of water. 
• In some areas, people need to travel long distances to collect water. 
• If water is scarce, it is very difficult to get food and fodder, 
• Water is precious. Let us not waste even a single drop of water. 
• We must preserve water not only for us but also for future generations. 
• So don’t wastewater.

1. The reaction between anhydrous copper (II) sulphate and water is used as a test for water. 

2. The white solid turns blue in the presence of water.

1. Boiling – Temporary hardness is easily removed from water by boiling. 

2. Adding washing soda – Washing soda is used to remove permanent hardness of water. 

3. Ion-exchange – This converts hard water into soft water. 

4. Distillation – Temporary and permanent hardness both can be removed by the method of distillation.

Settling – Oxygenating – Filtration – Chlorination.

Filtration, purification, chlorination

We must crush and throw the empty drinking water bottles into a bin, so that it cannot be reused.

The date of bottling and the period for which the water can be safely used is printed on the bottle. Therefore, it is important to read the information when we buy a bottle of drinking water.

Natural water contains many unwanted substances: It is necessary to purify water before it is used for drinking and cooking. The water with unwanted substances and bacteria used for drinking and cooking can cause many diseases like Typhoid, Cholera, Jaundice and Diarrhoea.

Boiling is the process by which temporary hardness is easily removed from water

1) C 

2) D 

3) A 

4) E 

5) B

At homes, the tap water is filtered and boiled to purify it for drinking.

1. Liquid state 

2. Solid-state 

3. Gaseous state.

Due to scarcity of water there will be drought – like condition.

The people and animals will die of thirst and hunger. Plants and farms will wither and die therefore no food will be available. This will lead to famine

Pond: Lawns and soil based plants require watering and It’s good to have some where for rainwater to go instead of being wasted. 

Reservoirs: Use to generate electricity, irrigation, human consumption, industrial use, agriculture.

(a) Sulphates and Chlorides

The hardness due to the presence of chloride and sulphate salts of calcium and magnesium is known as permanent hardness of water. 

Removal of hardness: 

1. Adding washing soda:

1. Washing soda is used to remove permanent hardness of water. 

2. It converts chlorides and sulphates into insoluble carbonates. 

3. These insoluble carbonates are removed by filtration.

2. Distillation: 

1. Temporary and permanent hardness both can be removed by the method of distillation.

2. The water obtained after distillation is called distilled water. 

3. It is the purest form of water.

Oceans and seas cover Two third of the earth.

Aquatic plants make use of dissolved CO₂ for photosynthesis.

The ultimate source of all water on the earth is rain.

1.The two forms of well tube well and open well

2.Rainwater is the major sources of water on the earth.

Water is used for many purposes like drinking, bathing, cooking and washing. It is also needed in large quantity for agriculture and industry.

The disadvantages of hard water:

1. It is not good for washing clothes. It forms scum with soap and detergents, which makes the soap ineffective and also spoils the clothes further. 

2. It damages the utensils and containers in which it is stored and forms a hard layer. 

3. It forms scales on the machine parts used in industries and decreases their efficiency. 

4. It results in stomach ailments if consumed for a long period.

1. True

2. False 

Correct statement: Temporary and permanent hardness both can be removed by the method of distillation.

3. True

4. True

5. False

Correct statement: During electrolysis, hydrogen and oxygen are obtained in the ratio 2:1.

1. Water is universal solvent.

2. 97.2% of water a available on the earth is present in seas & oceans.

3. Boiling point of water is 100 degreeC.

Reason: 

1. Air dissolved in water is important for the aquatic animals to survive. 

2. Aquatic animals extracts the oxygen form the water and expels water. 

3. They can breathe in water only through the dissolved oxygen present in water.

Reason: 

Hard water damages the utensils and containers in which it is stored and forms a hard layer.

Since water can dissolve various substances and widely used for preparing solutions it is a universal solvent.

Reason:

1. Water has a unique property to dissolve more substances than any other liquids. 

2. It can dissolve solids such as salt and sugar, liquids such as honey and milk and gases such as oxygen and carbon dioxide in it. 

3. Water can dissolve more number of substances than any other solvent. 

4. Therefore, it is called as universal solvent.

Most substances dissolve in water: Take some water in a beaker. Add a spoonful of salt to the water and stir well. You cannot see the salt. The salt is mixed up with the water. Hence, it is called universal solvent.

As water can dissolve in most of the substances, solids, liquid and gaseous. Therefore it is called universal solvent.

(a) Water has maximum density at 4°C. Ice is lighter than water therefore it floats on water. 

(b) This anomalous property of water enables aquatic plants and animals to survive in colder regions of world because even when the water of ponds, lakes, river freezes it freezes on the top but remains a liquid below ice layer. 

(c) Sometimes we see water droplets on the outer surface of the glass containing ice-cold water, this is because the water vapour presents in’air, on coming in contact with the cold glass of water, loses energy and gets converted into liquid state, which we see as water droplets.

Taste of water is tasteless i.e. flat. It is because distilled water does not contain any salt or mineral required for our body. So it is not potable water.

1. to kill the germs