Ec Unit-1 Bits (1) PDF

## WATER AND ITS TREATMENT ### III. MULTIPLE CHOICE QUESTIONS: 1. Temporary hardness in water is removed by * filtration * sedimentation * boiling * coagulation 2. Blow-down operation causes the removal of * scales * sludges * acidity * sodium chloride 3. Solubility...

## WATER AND ITS TREATMENT ### III. MULTIPLE CHOICE QUESTIONS: 1. Temporary hardness in water is removed by * filtration * sedimentation * boiling * coagulation 2. Blow-down operation causes the removal of * scales * sludges * acidity * sodium chloride 3. Solubility of calcium sulphate in water * increases with rise of temperature * decreases with rise of temperature * remains unaltered with rise of temperature * does not adopt any definite pattern with rise of temperature 4. Permanent hardness of water cannot be removed by * treatment with lime soda * by permutit process * boiling * ion-exchange process 5. Hard water is unfit for use in boilers for generating steam because * its boiling point is higher * hardwater does not produce lather inside the boiler * water decomposes into $O_2$ and $H_2$ * it produces scales inside the boiler 6. Estimation of hardness water by EDTA method is used to determine * alkaline hardness * temporary hardness only * permanent hardness only * all the above 7. Hardwater can be softened by passing it through * lime stone * sodium hexameta phosphate * ion-exchange resin * sodium silicate 8. Calgon is a trade name given to * sodium silicate * sodium hexametaphosphate * sodium meta phosphate * calcium phosphate 9. Brackish water mostly contains dissolved * calcium salts * magnesium salts * turbidity * sodium chloride 10. The method by which the ions are pulled out of salt water by direct current, and employing thin, rigid membrane pair is called * electro dialysis * reverse osmosis * zeolite * ion exchange 11. The purification of brackish water by reverse osmosis is also called as * super-filtration * supra-filtration * hypo-filtration * filtration 12. One part of $CaCO_3$ equivalent hardness per 105 parts of water is called * degree Clark * ppm * degree French * mg/l 13. Boiler corrosion caused by using highly alkaline water in a boiler is called * corrosion * boiler corrosion * caustic embrittlement * erosion 14. Caustic embrittlement can be avoided by using * sodium phosphate * hydrogen * ammonium hydroxide * sodium sulphate 15. Caustic embrittlement is a type of * boiler corrosion * conditioning * scale formation * sludge formation 16. The soft, loose and slimy precipitate formed within the boiler is called * scale * sludge * embrittlement * coagulation 17. Sodium meta aluminate used in internal treatment of boiler water produces flocculant precipitates of * $Mg(OH)_2$ and $Al(OH)_3$ * $NaOH$ and $Al(OH)_3$ * $Ca(OH)_2$ and $Al(OH)_3$ * $Mg(OH)_2$ and $Ca(OH)_2$ 18. In low pressure boilers carbonate conditioning of boiler feed water is carried out to remove * calcium bicarbonate * calcium sulphate * calcium chloride * calcium nitrate 19. The process of allowing water to stand undisturbed in big tanks for setting of the suspended particles due to force of gravity * coagulation * conditioning * sedimentation * screening 20. The composition of alum is * $K_2SO_4. Al_2(SO_4)_3. 24 H_2O$ * $K_2(SO_4)_3. Al_2.(SO_4)_3. 24 H_2O$ * $K_2SO_4. Al_2(SO_4)_3. 20 H_2O$ * $K_2SO_4. Al_2SO_4. 24 H_2O$ 21. Ferrous sulphate is commonly used in the treatment of municipal water for * filtration * flocculation * sedimentation * disinfection 22. Liquid chlorine is a most effective * disinfectant * coagulant * flocculant * sedimentation 23. Disinfection by ozone is due to liberation of * oxygen * nascent oxygen * molecular oxygen * oxide 24. The formula of chloramine is : * $ClNH_2$ * $NHCl_2$ * $NCl_3$ * $NH_2Cl_2$ 25. Phosphate conditioning of boiler feed is carried out by * $Na_3PO_4$ * $Ca_3(PO_4)_2$ * $Mg_3(PO_4)_2$ * $H_3PO_4$ 26. Tannins and agar-agar are used for * phosphate conditioning * carbonate conditioning * colloidal conditioning * calgon conditioning 27. The external treatment of boiler water feed done by * lime-soda process * sodium sulphate treatment * calgon process * sodium aluminate treatment 28. The process of wet-steam formation is called * foaming * priming * corrosion * caustic embrittlement 29. Mechanical steam purifiers avoid * corrosion * priming * scale formation * sludge formation 30. Castor oil is a * antiskinning agent * antifoaming agent * anti-ageing agent * anti-corrosive agent 31. The largest source of water is * lake water * river water * rain water * sea water 32. One of the following impurity is introduced into rain water due to the decomposition of plant and animal remains in water. * Organic impurities * Dissolved impurities * Floating impurities * Colloidal impurities 33. A water sample found to possess 16.2 mg/l of $Ca(HCO_3)_2$. Its hardness in terms of $CaCO_3$ equivalents is * 100 * 10 * 16.2 * 1000 34. Hardness of water is caused due to the presence of * undissolved salts of $Ca^{2+}$ and $Mg^{2+}$ * dissolved sulphates of potassium * dissolved salts of $Ca^{2+}$ and $Mg^{2+}$ * undissolved $CaCO_3$ 35. Which of the following methods separates both ionic and non-ionic impurities from water? * Electrodialysis * Deionisation * Reverse osmosis * Zeolite process 36. Potable water treatment does not involve * demineralisation * sedimentation * filtration * disinfection 37. The cofficient of thermal expansion of boiler plant is * more than boiler scale * less than boiler scale * equal to boiler scale * no comparison between two 38. Which of the following salts cause least hardness to water when converted to $CaCO_3$ equivalents? * 10 mgs of $CaCO_3$ * 19 mgs of $CaSO_4$ * 10 mgs of $MgCl_2$ * 10 mgs of $CaCl_2$ 39. Ultraviolet rays are used in the treatment of water for * Filtration * Sedimentation * Screening * Sterilisation 40. One of the following chemical act on both coagulant and softening agent * lime * soda * alum * sodium aluminate 41. The ion-exchanging resins used for softening of water are * cross-linked polymers with microporous structure * branched polymers with porons structure * cross-linked polymers with non-porous structure * branched polymers with non-porous structure 42. One of the following is an example of cation exchanging resin * copolymer of phenol formaldehyde or amine formaldehyde. * copolymer of styrene-divinyl benzene. * copolymer of phenol formaldehyde or styrene. * copolymer of amine formaldehyde or divinyl benzene. 43. Trisodium phosphate used for phosphate conditioning is * acidic * weakly acidic * weakly alkaline * alkaline 44. The membrane filtration adopted in reverse osmosis is also called * super filtration * supra filtration * ultra filtration * hypo filtration 45. A cation selective membrane consists of * positively changed functional groups * neutral functional groups * negatively changed functional groups * either positive or negative groups 46. One of the technique is followed in deflourination of drinking water by Nalgonda method * sedimentation * biological oxidation * screening * distillation 47. Deflourination is a technique depending on one of the mode of action * process * absorption process * desorption * condensation 48. One of the following is reference electrode is used in the estimation of flouride by ion-selective method. * calomel * hydrogen * silver or silverchloride * quinhydrone electrode 49. One of the following treat is classified under secondary treatment of sewage * screening * sedimentation * incineration * biological treatment 50. A shallow pit where the sludge is disposed is called * lagoon * ditch * tank * chamber ### IV. FILL IN THE BLANKS: 1. On addition of chlorine to water ______acid is produced which is powerful germicide. 2. Hardness of water is due to the dissolved salts of ______and ______. 3. The chemical which removes dissolved oxygen of water without adding hardness is ______. 4. Hardness of water is expressed in equivalents of ______. 5. In lime-soda process of softening, calcium and magnesium ions are precipitated as ______and ______. 6. Sodium aluminate is used as ______during purification of water. 7. Anion exchange resins are regenerated by using ______process. 8. Best method of removing hardness of water is ______. 9. Among chloramine, bleaching powder and chlorine ______is a powerful disinfectant. 10. The hardness of water in $CaCO_3$ equivalents containing $MgSO_4$ (mol. wt. 120) with concentration 12 mg/l is ______. 11. Presence of residual ______in boiler water causes caustic embrittlement. 12. ______causes the flow of solvent from lower concentration to higher concentration, which is separated by a semipermeable membrane. 13. In lime-soda process the addition of lime cannot remove ______hardness of water. 14. In phosphate conditioning if boiler feed water is too alkaline ______is used for internal conditioning. 15. Priming and foaming in boilers produce ______steam. 16. Cation exchange resin contains ______mobile ions. 17. The hardness of a sample of water is 10 ppm, which can be expressed as ______degree clarke. 18. A sample of water contains 11.1 mg/l of $CaCl_2$. Its hardness of $CaCO_3$ equivalent is ______. 19. ______is used as an indicator in the determination of hardness by EDTA method. 20. To maintain the pH between 9-10 during complexometric titration, estimation of hardness of water is ______. 21. Temporary hardness of water can be removed by ______. 22. Calgon treatment is used for the removal of dissolved ______. 23. The chemical structure of zeolite is ______. 24. Natrolite is a ______zeolite. 25. Ion free water is known as ______. 26. The exhausted zeolite is regenerated by ______. 27. ______is a process of allowing water to stand undisturbed in big tanks. 28. $Al_2(SO_4)_3$ alum produce ______as flocculant precipitates during softening of water. 29. ______membranes are selected for efficient separation of ions. 30. The presence of even small amounts of $MgCl_2$ will cause ______of boiler plate to a large extent. 31. ______is considered to be the naturally distilled water. 32. ______water contain the largest concentration of dissolved impurities. 33. Rain water picks up $CO_2$, $O_2$ etc., from atomsphere which introduces ______impurities into water. 34. The pure water is pushed out through a semipermeable membrane during ______. 35. Extra-pure water can be obtained by using ______. 36. A semipermeable membrane allows the flow of ______. 37. Chlorine, when treated with water produce ______acid, which acts as a powerful germicide. 38. The exhausted anion exchanging resin is regenerated by ______. 39. Rain water picks up gases like $CO_2$, $O_2$ etc. from ______. 40. The suspended and colloidal impurities are allowed to settle under gravitaion in ______process. 41. Among the dissolved gases, ______ is the most corroding impurity. 42. Zeolites are ______. 43. A copolymer of ______or ______is used as an anion exchanging resin. 44. Deionisation must be followed by ______. 45. If the alkalinity of boiler water is ______, sodium dihydrogen phosphate conditioning is carried out. 46. $CaCO_3$ is an ______salt when present in water. 47. Disinfectation by bleaching powder is also called ______. 48. $CaSO_4$ is ______soluble in cold water. 49. The precipitates of $CaCO_3$ and $Mg(OH)_2$ are very fine and causes ______problems. 50. The most preferred request for phosphate conditioning is ______. 51. In high pressure boilers the excess $Na_2CO_3$ remained during carbonate conditioning is converted to ______. 52. When the sewage contains oxidisation impurities beyond biological oxidation, then ______is carried out. 53. During Nalgonda process of removal of flourides employs ______principle. 54. Acetic acid and sodium hydroxide solution is used as a ______in the Nalgonda technique. 55. The oxygen required for the biological oxidation of bacteria present in sewage water is called ______. ### V. INDICATE TRUE OR FALSE FOR THE FOLLOWING: 1. Rain water is the purest form of natural water. **[T/F]** 2. Suspended impurities are present in natural water. **[T/F]** 3. Dissolved oxygen do not cause corrosion to boiler plate. **[T/F]** 4. Calcium and magnesium salts in water are removed by lime soda process. **[T/F]** 5. It is possible to remove permanent hardness of water by boiling. **[T/F]** 6. Chloramine is better than chlorine for sterilisation. **[T/F]** 7. The common unit to express hardness of water is ppm. **[T/F]** 8. Sludge is a soft, loose, slimy precipitate formed inside the boiler. **[T/F]** 9. $NH_4Cl$ and $NH_4OH$ buffer is used to maintain pH 12. **[T/F]** 10. Water softened by zeolite process causes caustic embrittlement. **[T/F]** 11. Hardness of water is expressed in calcium chloride equivalents. **[T/F]** 12. Hot lime-soda process is better than cold process. **[T/F]** 13. The presence of $CO_2$ in water produces carbonic acid. **[T/F]** 14. The process of removing hardness producing salts is called softening. **[T/F]** 15. Hydrated sodium aluminium silicate is called zeolite.**[T/F]** 16. The process of removing common salt from water is called salination. **[T/F]** 17. Addition of calgon to boiler water prevents calcium sulphate scale formation. **[T/F]** 18. Hard water precipitates, soap as calcium soap.**[T/F]** 19. Reverse osmosis removes all ionic, non-ionic and colloidal impurities from water. **[T/F]** 20. Dissolved calcium bicarbonate in water causes permanent hardness. **[T/F]** 21. pH of acidic water is more than 7. **[T/F]** 22. Hard water softened by EDTA method. **[T/F]** 23. Break point chlorination gives the exact amount of chlorine to be added to raw water. **[T/F]** 24. The exhausted permutit is regenerated by $ZnCl_2$. **[T/F]** 25. Extra pure water is obtained by electrodialysis. **[T/F]** 26. Coagulant helps in setting of colloidal particles only. **[T/F]** 27. A permeable membrane allows the flow of solvent molecules. **[T/F]** 28. Calgon is a trade name of sodium hexa meta phosphate. **[T/F]** 29. Calgon conditioning is better than phosphate conditioning. **[T/F]** 30. Water is softened before using in boilers by external treatment. **[T/F]** 31. Chemically oxidisation impurities of sewage is measured by COD. **[T/F]** 32. Nalgonda process is for the removal of chlorine from drinking water. **[T/F]** 33. Silver electrode is used as reference electrode for the estimation flourine by ion-selective electrode. **[T/F]** 34. Activated sludge process is for the oxidation of biological impurities in sewage water. **[T/F]** 35. Screening is a preliminary treatment. **[T/F]** ### III. MULTIPLE CHOICE QUESTIONS: | 1) | c | 2) | b | 3) | b | 4) | c | 5) | d | 6) | d | 7) | c | 8) | b | 9) | d | 10) | a | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | 11) | a | 12) | c | 13) | c | 14) | d | 15) | a | 16) | b | 17) | a | 18) | b | 19) | c | 20) | a | | 21) | b | 22) | a | 23) | b | 24) | a | 25) | a | 26) | c | 27) | a | 28) | b | 29) | b | 30) | b | | 31) | d | 32) | a | 33) | b | 34) | c | 35) | c | 36) | a | 37) | a | 38) | b | 39) | d | 40) | d | | 41) | a | 42) | b | 43) | d | 44) | a | 45) | c | 46) | a | 47) | b | 48) | c | 49) | d | 50) | a | ### IV. FILL IN THE BLANKS: 1. hypochlorous 4. calcium carbonate 7. sodium hydroxide 10. 10 mgl 1=) calcium permanent 15. wet 18. 10 mgl 21. boiling 23. $Na_2O. Al_2O_3, nSiO_2. y H_2O$ 25. deionised or demineralised water 27. Sedimentation 30. corrosion 33. dissolved gas 36. solvent molecules 39. atmosphere 42. cation exchangers 44. degasification 47. hypo-chlorination 50. trisodium phosphate 53. flocculation 2. calcium and magnesium 5. $CaCO_3$ and $Mg(OH)_2$ 8. ion-exchange process 11. $NaOH$ or caustic soda 14. $NaH_2PO_4$ or sodium dihydrogen phosphate 16. $H^+$ 19. Eriochrome black - T 22. $CaSO_4$ 24. natural 26. $NaCl$ 28. $Al(OH)_3$ 29. Ion-selective 31. Rain water 34. reverse osmosis 37. hypochlorous 40. sedimentation 43. phenol formaldehyde and amine formaldehyde 45. high 48. more 51. $NaOH$ 54. buffer 3. hydrazine 6. coagulant 9. chlorine 12. Osmosis 17. 0.7 °Cl 20. $NHCl_2$, $NH_2OH$ 32. Sea water 35. electrodialysis 38. $NaOH$ 41. oxygen 46. insoluble 49. after deposition 52. chemical oxidation 55. BOD ### V. TRUE OR FALSE QUESTIONS: | 1) | T | 2) | T | 3) | F | 4) | T | 5) | F | |---|---|---|---|---|---|---|---|---|---| | 6) | F | 7) | T | 8) | T | 9) | F | 10) | T | | 11) | F | 12) | T | 13) | T | 14) | T | 15) | T | | 16) | F | 17) | T | 18) | T | 19) | T | 20) | F | | 21) | F | 22) | F | 23) | T | 24) | F | 25) | T | | 26) | F | 27) | T | 28) | T | 29) | T | 30) | T | | 31) | T | 32) | F | 33) | T | 34) | T | 35) | T |