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The poem ‘Water’ attempts to depict the struggle, the anguish, the suffering and the humiliation suffered by the Dalits to get their rightful share of water. The speaker, having recollected all the incidents related to their humiliations and their suffering, talks about how water can be a source of retributive justice. The speaker declares that water is not a simple thing; it can give life but can also devour lives. She then declares in a vengeful tone that the water that could not serve to quench the thirst of the parched throats (of Dalits) became the killer tsunami wave and swallowed the whole village after village.

The speaker declares that ‘water’ is so powerful that it treats the ‘poor’ as its playthings. Sometimes, many villages suffer from drought and become dry deserts killing poor people. It may also come in the form of floods and drown them. Thus, the poet depicts the destructive nature of water.

The flow of water can bring silt to form fertile land which is beneficial for mankind. It can also cause soil erosion and thus destroy agriculture. These are respectively beneficent and destructive roles of the flow of water. 

जले.को बहाव उपजाऊ भूमि के निर्माण हेतु अपने साथ उपजाऊ मिट्टी लेकर आ सकता है जो कि मनुष्य के लिए लाभदायक है। यह मृदा-अपरदन भी करता है जो कृषि को नष्ट कर सकती है। ये जल के बहाव की क्रमशः लाभदायक व हानिकारक भूमिकाएँ हैं।

(d) Building concrete roads

(a) Three major sources of natural water : 

1. Surface water (sea water) 

2. Above surface water (rain) 

3. Underground water (springs) 

(b) Four sources of surface water sources : 

1. Ocean water 

2. River water 

3. Lake water 

4. Glaciers 

(c) Two sources of underground water : 

1. Well water 

2. Spring water

Water is present in the form of water vapours in the atmosphere.

Sea water contains highest concentration of salt.

The ways in which we can conserve water are as follows : 

1. Use a bucket for taking it. 

2. Make sure, water does not overflow from overhead tanks of your house. 

3. Close the tap when you are brushing your teeth.

4. Wash fruits, vegetable in a bowl of water, rather than under a running tap. Water used for washing vegetables may be used to water plants in the garden.

(a) sodium carbonate 

(d) sodium sulphate 

(e) table salt 

(j) honey

Match the statements in List I, 1-10 with their correct answer in List II, 

(d) All of these

1. Plastic sheets are used in agriculture to grow vegetables. 

2. At the end of the season, these plastic sheets are ploughed back into the soil. 

3. The plastic sheets break into tiny pieces and get eaten by earthworms, which is harmful to their health and that of soil.

H₂O is the chemical formula of water.

Pure water is a clear and transparent liquid: 

1. Pure water boils at 100° C at one atmospheric pressure. 

2. Pure water freezes at exactly 0°C at one atmospheric pressure. 

3. Pure water has a density of 1 gm/cm³.

1. House hold detergents 

2. Domestic sewage 

3. Domestic waste and plastics 

4. Agricultural activities 

5. Oil spills 

6. Industrial waste.

Zn + H₂SO₄ → ZnSO₄ + H₂ 

2H + O₂ → 2H₂O

The sources and effects of domestic and industrial pollutants.

(a) False 

Correct: Water is aL compound.

(b) False 

Correct: Tap water contain dissolved impurities.

(c) False 

Correct : Alum is commonly used for settling down of suspended impurities

(d) False 

Correct : Distillation is a good method-for purifying water for medicinal purpose.

The purest form of natural water is   

3. rainwater  

The smallest particle of water is ‘molecule’. The molecule of water is made up of two atoms of hydrogen (H₂) and one atom of oxygen (O). Both of these atoms combine to form a compound called water i.e., H₂ + O → H₂O.

Water constantly moves from the earth to the air and again comes down to the earth in the form of rain. Water from seas, rivers lakes, ponds, puddles and streams evaporates due to the heat of the sun. Plants to give out large amounts of water from their leaves. Water vapors rise up. The air higher up in the atmosphere is cooler which cools the water vapors and condenses to form tiny droplets of water on small dust particles. These droplets combine to form clouds. The clouds get cooled further, the water drops become bigger. When they become too heavy, they fall on the earth as rain. The rainwater again forms seas, rivers, lakes, ponds and streams and it again evaporates to the air, thus the water-cycle in nature continues.

(i) Water cycle helps in regulating weather on the earth.

(ii) Water cycle makes water available in various forms on the earth.

(i) Oceans (ii) Seas

(iii) Rivers (iv) Lakes

1. When sulfur dioxide dissolves in water sulfurous acid is formed. 

SO₂ + H₂O → H₂SO₃ 

2. When potassium oxide dissolves in water-potassium hydroxide is formed 

KO + H₂O → KOH 

3. When calcium oxide dissolves in water calcium hydroxide is formed. 

CaO +H₂O → Ca(OH)₂ 

4. When carbon dioxide dissolves in water carbonic acid is formed. 

CO₂+ H₂O → H₂CO₃

Presence of water soluble calcium and magnesium bicarbonate sulfates and chlorides cause hardness in water.

(a) Water drops appear on the outer surface of a glass containing cold water. Condensation
(b) Steam rising from wet clothes while they are ironed. Evaporation
(c) Fog appearing on a cold winter morning. Condensation
(d) Blackboard dries up after wiping it. Evaporation
(e) Steam rising from a hot girdle when water is sprinkled on it. Evaporation

(a) Water vapour is present in air only during the monsoon. (False)
(b) Water evaporates into air from oceans, rivers and lakes but not from the soil. (False)
(c) The process of water changing into its vapour, is called evaporation. (True)
(d) The evaporation of water takes place only in sunlight. (False)
(e) Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooler. (True)

Sodium is to be kept under kerosene as it can react with oxygen and water vapors present in air and kerosene has no affinity towards sodium.

The rate of evaporation increases with increase in temperature. So, near the anghiti or heater, the rate of evaporation will be higher and the uniform will dry up quickly.

Washing soda loses its crystal structure quickly as it loses water when exposed to air of moderate humidity. It is efflorescent substance.

Yes, spreading it near heater will surely help as heater and anghiti are source of heat which vapourize the water of the wet clothes and thus help in drying.

The puddle of water seen around the cooled bottle of water is due to the condensation effect as the water vapour present in the air around the bottle get condensed after colliding with bottle.

When the air moves up, it gets cooler and cooler and after reaching sufficient height the air becomes so cool that the water vapour present in it condenses to form tiny drops of water called droplets which remain floating in air and thus clouds are formed.

Water vapour also gets released during exhalation process along with carbon dioxide The water vapour gets attached with the glasses of the spectacles and then condenses in the presence of air surrounding it and thus making it wet.

When we breathe out, moist air comes out (along with energy and carbon dioxide) which make the glasses wet (as water vapours get condense on glass).

Three main causes of water pollution : 

1. Addition of waste products from homes. 

2. Addition of waste products from agriculture. 

3. Addition of waste from industries.

 4. Addition of sewage in water bodies.

When a solute stops dissolving into a solvent beyond a particular limit, the formed solution is said to be saturated solution.

(i) Cholera 

(ii) Typhoid 

(iii) Hepatitis

1. Acid is added to water before electrolysis to make it good conductor of electricity.

2. The constituents of water are hydrogen and oxygen. The molecular formula is H₂O.

3. When water is cooled it contracts and its density, increases until the temperature reaches 4°C, on further cooling water starts expanding with the decrease in its density. This is anomalous phenomenon. The aquatic organisms can live there easily.

4. Hydrogen and oxygen gases are dissolved in water.

Water pollution— The water present in rivers, ponds, lakes and streams, comes from rain and the melted snow of the mountains. As it flows the down the plains, it picks up many dissolved and suspended impurities and gets polluted

Causes of water pollution:

• Industrial and agricultural processes— Fertilizers, pesticides, insecticides and other chemicals used in cultivated fields, get dissolved in water when it flows over these fields. They make the water unfit for consumption.

• Nuclear and thermal power plants— Power plants discharge the hot water often containing chemicals into water streams. It is harmful to aquatic life.

• The discharge of sewage and garbage— The discharge of sewage and garbage into river water is one of the major causes of water pollution.

Prevention of water pollution—

• Make people aware of pollution.

• Make sanitary facilities available is rural areas and city slums.

• Domestic sewage should be treated before being discharged into rivers.

• The solid matter separated from sewage can be used to generate biogas.

• The waste products of industries should be treated before they are discharged into rivers and other water bodies.

• We should stop using substances like detergents, pesticides, polythene etc.

Main causes of water pollution are:

• Chemical waste, industrial waste and agricultural processes.

• Thermal waste from nuclear and thermal power plants.

• Sewage and garbage.

Prevention of water pollution:

• Domestic sewage should be treated before being discharged into rivers.

• Using of non-biodegradable substances like detergents should be stopped.

• Trees and plants must be planted along the banks of rivers.

• Purification of water bodies should be carried out.

• The waste products of industries should be treated before they are discharged into rivers.

(a) Alcohol is mixed with the water used in car radiators to prevent it from freezing ki cold weather. Because it lowers the freezing point of water.

(b) Icebergs float in ocean water because the density of ice is less than water.

(c) Carbonated drinks are bottled under high pressure because the solubility of carbon dioxide increases with pressure.

When it rains heavily water runs into streets, drains and wasted we can not make use of it. Our purpose is to catch this rain water, store it for future use when we actually need it. For this harvesting of rain water should be done. Rain water is collected from the roofs and verandas of the buildings with the help of pipes and carried to tanks for storage and is used at the time of need when it is not rainin

Four ways to conserve water: 

1. Do not allow water to drip from defective taps. 

2. More dams should be built. 

3. More plantation should be done as plants help in bringing rain. 

4. Wastage of water should be avoided. 

5. Close the tap when you are brushing your teeth. Rather use a mug. Close the tap when you are washing clothes, open the tap only when you need it. Reduce, Reuse and recycle should be our mantra

Differences between water and air : 

Water :

1. Water is liquid and can exist in three states i.e. solid-ice, liquid-water, gas – vapours. 

2. Is a compound. 

3. H₂O is its formula. 

Air : 

1. Air is gaseous and can exist in liquid state when cooled under pressure. 

2. Is a mixture. 

3. Has no formula.

Water is indispensable for all the living-organisms. 70% of human body consists of water. Water sustains several life processes in humans and animals. Water helps in controlling our body temperature. Water also generates electricity. Water keeps the environment and atmosphere mild when it is too hot.

Boiled water is deprived of oxygen i.e. there is no oxygen. For want of oxygen animals die in boiled water.

(a) Solute— The substance which dissolves or disappears in the solvent i.e. liquid to form a solution is called a solute. e.g. sodium chloride. . 

(b) Solvent— The liquid or medium of dissolution which allows the solute to dissolve in it, so as to form a solution is called a solvent, e.g. water. 

(c) Solution— A homogenous mixture of a solute in a solvent is called a solution.