Exercise III on Water Class 6 Concise Chemistry ICSE Solutions Ch-7. In this article you would learn how to solve Exercise III on Water with hint and reason. Visit official Website CISCE for detail information about ICSE Board Class-6.
Exercise III on Water Class 6 Concise Chemistry ICSE Solutions
| Board | ICSE |
| Publications | Selina Publication |
| Subject | Chemistry |
| Class | 6th |
| Chapter-7 | Water |
| Book Name | Concise |
| Topics | Solution of Exercise III |
| Academic Session | 2025-2026 |
Exercise III on Water
Objective Type Questions
Que-1: Chlorination of water is done to :
(i)kill germs
(ii)remove the suspended impurities
(iii)remove the dissolved impurities
(iv)none of the above
Ans- kill germs
Reason- Chlorination of water is done to kill germs, Water is passed into a chlorination tank to kill all the germs present in it.
Que-2: A method used to kill harmful germs present in water is:
(i)sedimentation
(ii)decantation
(iii)boiling
(iv)filtration
Ans- boiling
Reason- Boiling kills harmful germs and makes water safe for drinking.
Que-3: Sea water is not fit for drinking because it contains a large amount of:
(i)suspended impurities
(ii)sugar
(iii)dissolved salts
(iv)none of the above
Ans- dissolved salts
Reason- Sea water contains a large amount of dissolved salts, which make it unfit for drinking.
Que-4: The gas which adds taste to water is:
(i)oxygen
(ii)nitrogen
(iii)hydrogen
(iv)carbon dioxide
Ans- carbon dioxide
Reason- Carbon dioxide dissolved in water gives it a pleasant taste.
Que-5: Distilled water is:
(i)salty
(ii)sweet
(iii)sour
(iv)tasteless
Ans- tasteless
Reason- Distilled water is free from dissolved salts and gases, so it has no taste.
Que-6: Which of the following is a water-borne disease?
(i)Influenza
(ii)Typhoid
(iii)COVID-19
(iv)Malaria
Ans- Typhoid
Reason- Typhoid spreads through contaminated water and food, so it is a water-borne disease.
Short Answer Questions
Que-1: Name:
(i) Two chemicals used to destroy germs present in water.
(ii) Two diseases which spread through impure water.
(iii) A chemical used for loading.
(iv) Two substances which add taste to water.
(v) Two household methods to get safe drinking water.
Ans- (i) Chlorine and Potassium permanganate
(ii) Typhoid and Cholera
(iii) Alum (Potash alum)
(iv) Oxygen and Carbon dioxide
(v) Boiling and Filtration
Que-2: Define:
(i) Sterilisation
(ii) Sedimentation
(iii) Loading
(iv) Aeration
Ans- (i) Sterilisation: The process of destroying harmful germs present in water to make it safe for drinking is called sterilisation.
(ii) Sedimentation: The process by which heavier insoluble impurities settle down at the bottom of water when it is left undisturbed is called sedimentation.
(iii) Loading: The process of adding alum to water to make fine suspended impurities settle down faster is called loading.
(iv) Aeration: The process of mixing air with water to improve its taste and remove unpleasant odours is called aeration
Que-3: What is the taste of distilled water? Why is it not potable ?
Ans- Distilled water is tasteless. Distilled water is not considered potable for regular drinking because it lacks dissolved minerals and gases such as oxygen and carbon dioxide, which give water its pleasant taste and make it more suitable for drinking. It is mainly used in laboratories, batteries, and scientific work.
Que-4: Answer in brief:
(i) Why is river water unfit for drinking ?
(ii) Why is tap water a mixture ?
(iii) What is mineral water?
(iv) What is the purpose of adding bleaching powder to water supplied to the town?
(v) How is chemically pure water obtained in the laboratory?
(vi) How is water in a swimming pool kept free from germs?
(vii) Why is water important for plants and animals?
Ans- (i) River water contains suspended impurities, dissolved salts, and disease-causing germs, so it is unfit for drinking without treatment.
(ii) Tap water contains dissolved salts, minerals, gases, and other impurities mixed with water, so it is a mixture.
(iii) Mineral water is purified drinking water that contains dissolved minerals beneficial to health.
(vi) Bleaching powder is added to destroy harmful germs and make the water safe for drinking.
(v) Chemically pure water is obtained by the process of distillation.
(vi) Water in a swimming pool is kept free from germs by adding chlorine.
(vii) Water is essential for life. It is needed for various life processes such as digestion, transportation of nutrients, excretion, and photosynthesis in plants.
Long Answer Questions
Que-1: Name the steps involved in the purification of drinking water supplied in cities and towns.
Ans- The water supplied to cities and towns is purified in water treatment plants before it reaches our homes. The main steps are:
(i)Sedimentation: Water is stored in large tanks where heavy insoluble impurities like sand, mud, and pebbles settle at the bottom.
(ii)Loading: Alum is added to water. It causes fine suspended impurities to clump together and settle down quickly.
(iii)Filtration: The clear water is passed through layers of sand and gravel filters to remove remaining suspended particles.
(iv)Sterilisation : Chlorine or bleaching powder is added to the filtered water to kill harmful germs and bacteria.
(v)Storage and Distribution: The purified water is stored in reservoirs and then supplied through pipelines to homes, schools, and other buildings.
Que-2: Give reason:
(i)Ice floats on water.
(ii)Marine life is able to survive in colder regions.
(iii)Water droplets can be seen outside a chilled water bottle.
Ans- (i) Ice floats on water because ice is less dense than water. When water freezes, it expands and its density decreases.
(ii) Marine life can survive in colder regions because water freezes only at the surface. The layer of ice floats on water and acts as an insulator, keeping the water below in the liquid state where aquatic organisms can live.
(iii) Water droplets are seen outside a chilled water bottle because water vapour present in the air condenses on the cold surface of the bottle, forming tiny droplets of water.
Que-3: What is potable water? List four characteristics of potable water.
Ans- Potable water is water that is safe and fit for drinking and domestic use. It does not contain harmful germs or harmful amounts of impurities.
Characteristics of Potable Water
(i)Free from disease-causing germs such as bacteria and viruses.
(ii)Clear, colourless and transparent, with no suspended impurities.
(iii)Odourless and pleasant in taste.
(iv)Contains dissolved minerals and salts in suitable amounts, making it safe and healthy for drinking.
Que-4: What are the three methods of removing germs from natural water? Explain.
Ans- Natural water obtained from rivers, lakes, ponds, and wells may contain harmful microorganisms such as bacteria, viruses, and other disease-causing germs. These germs can spread diseases like cholera, typhoid, and dysentery. Therefore, water must be treated before it is used for drinking. The three main methods of removing germs from natural water are:
(i) Boiling : Boiling is the simplest and most effective household method of purifying water. Water is heated until it boils and is kept boiling for about 10–15 minutes. The high temperature kills harmful microorganisms present in the water. After boiling, the water is allowed to cool and is stored in clean containers.
(ii) Chlorination : In this method, chlorine or bleaching powder is added to water. Chlorine acts as a disinfectant and destroys disease-causing germs. This method is widely used in water treatment plants, swimming pools, and public water supplies because it is economical and effective for large quantities of water.
(iii) Distillation : Distillation is a process in which water is boiled to convert it into steam. The steam is then cooled and condensed back into liquid water. Harmful germs and dissolved impurities remain behind in the original container, while the condensed water obtained is pure and germ-free. This method is commonly used in laboratories to obtain chemically pure water.
— : End of Exercise III on Water Class 6 Concise Chemistry ICSE Solutions :–
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