Ans. Soap is the sodium salt of a long chain carboxylic acid (fatty acid).
Hard water contains salts of magnesium and calcium. These ions react with the soap molecule to form an insoluble precipitate of calcium and magnesium salts of fatty acids called scum. As a result, a large amount of soap is wasted in scum formation. Thus, it reduces the efficiency of soap.
Q.7 What is meant by water pollution?
Ans. Water pollution is a contamination of water bodies (e.g. lakes, rivers, oceans and ground water). Water pollution occurs when pollutants are discharged directly or
indirectly
into water bodies without adequate treatment to remove harmful compounds.
Q.8 What is the difference between soft and hard water?
Ans. Soft water: Soft water is that produces good lather with soap.
Hard water: Hard water is that which does not produce lather with soap.
Q.9 What are the types of hardness in water?
Ans.
i. Temporary hardness is because of presence of bicarbonates of calcium and magnesium.
ii. Permanent hardness is because of presence of sulphates and chlorides of calcium and magnesium
Q.10 How temporary hardness is removed by boiling method?
Ans. Temporary hardness of water is easily removed by boiling water. On boiling calcium bicarbonate Ca(HCO) decomposes to produce insoluble calcium carbonate, which precipitates out of the solution
Q.12 What is hepatitis?
Ans. It is liver inflammation commonly caused by one of five viruses called hepatitis A,B,C,D and E. Hepatitis A and E can be transmitted by contaminated water.
Q.13 What is the importance of water in our daily life?
Ans. Its importance is because of two reasons. Firstly, it is an essential and major component of each and every living cell. For example, human body consists of about 70% water. Secondly, it provides an environment for animals, and plants that live in water. So, all living organisms owe their life because of water.
Q.14 Write characteristics of pure water?
Ans. Good quality water is colourless, odourless and tasteless. Hardness of water can be checked by washing. Soft water produces lather with water. Pure water has least conductivity
Q.15 What are the industrial effluents of water pollution?
Ans. Industrial effluents are one of the main causes of water pollution. It includes high toxic organic chemicals, inorganic salts, heavy metals. mineral acids, oil and greases, etc.
Q.16 What is meant by water borne diseases? How they are controlled?
Ans. Waterborne diseases are those diseases that spread because of drinking polluted water.
These diseases spread because of lack of proper sanitation arrangements. These diseases can be prevented by using safe water, properly disposing sewage and controlled use of toxic chemicals.
Q.17 What is the effect of detergents on scarcity of oxygen?
Ans. Household water in the sewage from toilets, baths, kitchens, etc. consists of detergents used for cleaning purposes. Detergent being non-biodegradable causes rapid growth of aquatic plants. When these plants die and decay, they consume O2 present in the water. Thus, aquatic life is badly affected because of scarcity of O2.
Q.18 Write a short note on agricultural effluents?
Ans. Agricultural effluents consist of fertilizers and pesticides. These substances provide nitrate and phosphate ions for rapid growth of aquatic plants. When these plants die and decay, their decomposition process consumes O2 of water. Thus, depletion of O2 causes damage to the aquatic life
Q.19 What is meant by fluorosis?
Ans. Fluorosis is a disease caused by the consumption of excess fluoride. Fluorosis can cause bones and teeth damage.
Q.20 Give composition of water molecule.
Ans. Water is composed of two elements: oxygen and hydrogen. One atom of oxygen combines with two atoms of hydrogen to form one molecule of water.
Q.29 Explain why non-polar gases are soluble in water?
Ans. Water can even dissolve non-polar (un-ionizable) gases like oxygen, hydrogen and nitrogen etc. through dipole-induced dipole forces.
Q.30 Which salts are responsible for hardness of water?
Ans. Rain water dissolves many salts of divalent cations like Mg, Ca, and anions like Cl, SO, HCO, and CO For example, gypsum (CaSO4.2H2O) and lime stone (CaCO3).
These salts make the water hard.
Q.31 What is the principle of removing permanent hardness of water?
Ans. The permanent hardness can only be removed by using chemicals calcium (Ca) and magnesium (Mg) are removed as "Insoluble salts by adding washing soda (Na2CO3) or sodium zeolite
Q.34 What do you mean by boiler scales? How are they removed?
Ans. Hard water is unfit for use in steam engines, boilers and turbines because insoluble calcium and magnesium salts are deposited inside. This hard deposited layer of calcium and magnesium salts is called as boiler scale, they can be removed by washing the boilers with washing soda, slaked lime and sodium zeolite.
Q.35 What is an industrial waste?
Ans. All the industrial units discharge their wastes (chemical and solid materials) either to open ground or to water channels this is called industrial effluent
Q.36 How water used as a cleaning agent in industries cause pollution?
Ans. Water used as cleaning agent in industries is directly discharged out. This water contains all kinds of toxic chemicals and detergents.
When these effluents or used water enter lakes, streams, rivers or oceans, they either ge dissolved or float suspended in water. Even they get deposited on the bed. This results in pollution of water.
Q.37 Why use of detergents is increasing day by day?
Ans. The use of detergents is increasing in houses and industries because detergents have strong cleaning action that of soap even in hard water. They can even work in acidic solution
Q.38 How decaying plants consume oxygen?
Ans. Decaying plants consume oxygen for the biodegradable.
Q.39 What is function of fertilizers?
Ans. Fertilizers are used to make up the deficiency of nitrogen, phosphorous ctc. of the soil because of intensive cultivation of crops in the recent years.
Q40 How pesticides cause water pollution?
Ans. Run-off from the agricultural land (where fertilizer and pesticides have been used) enters into ponds, streams or rivers. This water contains nitrate (NO and phosphate salts. These substances results in a rapid sunlight and air to reach the aquatic life.
When algae dies and decompose, bacteria consume oxygen of the water for decomposition.
As a result, oxygen depletes in water. Aquatic animals feel suffocation and ultimately die due to insufficient supply of oxygen.
In this way, pesticides play their role in water pollution,
Q.41 Define water borne diseases.
Ans. Diseases that spread because of drinking polluted water or eating food prepared with polluted water are called water borne diseases.
Q.42 What is dysentery?
Ans. Dysentery is an intestinal disease which is typically caused by certain bacteria or parasites. It is characterized by severe diarrhea that may be accompanied by blood or mucous
Q.43 Which of the bacteria causes the cholera?
Ans. Bacteria vibrio cholera causes cholera
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