Building Material Objective Question 1

 5.5. Pick up the correct statement from the following: 

(a) In argillaceous ingredient of ordinary cement, calcium carbonate predominates. 

(b) In calcareous ingredient of ordinary cement, clay predominates. 

(c) In ordinary cement, the argillaceous material, the clay predominates. 

(d) In ordinary calcareous material, the calcium carbonate predominates. (e) Both (c) and (d) 

5.6. Pick up the correct chemical formula of the ingredients of ordinary cement from the following: 

(a) Lime (CaO) (b) Silica (SiO2) (c) Alumina (Al2O3) 

(d) Calcium sulphate (CaSO4) 

(e) All of these are correct. 

5.7. In a good quality cement, the percentage of: 

(a) Lime is 62 (b) Silica is 62 (c) Alumina is 5 (d) Calcium sulphate is 4 

5.8. State which one of the following statements is correct. 

(a) The lime in excess makes the cement unsound. (b) The deficiency of lime decreases the strength of cement and causes it set quickly. (c) Both (a) and (b) (d) Neither (a) nor (b) 

5.9. The silica (SiO2), an important ingredient of cement. (a) imparts strength to cement due to formation of di-calcium silicates (2CaO . SiO2) and tricalcium silicates (3CaO, SiO2). (b) in excess increases the strength but prolongs the setting time. (c) both (a) and (b) (d) neither (a) nor (b) 

5.10. The alumina (Al2O3), an ingredient of cement: (a) imparts quick setting property to cement (b) acts as a cux to lower the clinkering temperature. (c) in excess reduces the strength of cement. (d) All of these. 

5.11. The calcium sulphate (CaSO4): 

(a) is not an ingredient of cement in the form of gypsum. 

(b) increases the initial setting time of cement. 

(c) decreases the initial setting time of cement. 

(d) All of these. 

5.12.Pick up the correct statement from the following: 

(a) The function of calcium sulphate (CaSO4) in cement is to increase its initial setting time. 

(b) An excess of magnesia (MgO) in cement makes it unsound. 

(c) Iron oxide (Fe2O3) imparts hardness and strength to cement. (d) All of these are correct.

5.13. An ordinary Portland cement (a) attains about 70% of its nal strength in 28 days. (b) attains about 90% of its nal strength in one year. (c) both (a) and (b) (d) neither (a) nor (b) 

5.14. Match list I with list II and choose the correct answer by using the codes given below the lists: List  I List  II (Cement compound) (Chemical formula) A. C3A 1. Dicalcium silicate B. C4AF 2. Tri calcium silicate C. C3S 3. Tetra calcium alumino-ferrite D. C2S 4. Teri calcium aluminate Codes: A B C D (a) 4 3 2 1 (b) 1 2 3 4 (c) 3 1 2 4 (d) 2 4 1 3 

5.15. When water is added to cement, the decreasing rate of reaction of the four minerals is as under: (a) C3A → C4AF → C3S → C2S (b) C4AF → C3S → C2S → C3A (c) C3S → C2S → C3A → C4AF (d) C3A → C4AF → C2S → C3S 

5.16. The quickest ingredient to react when water is added to cement: (a) Tri calcium aluminate (3CaO . Al2O3) (b) Tetra-calcium – alumino – ferrite (4CaO. Al2O3 Fe2 O3) (c) Tri calcium –silicate (3CaO. SiO2) (d) Dicalciam – Silicate (2CaO. SiO2) 

5.17.Pick up the correct statement from the following: (a) The hydration of tricalcium silicate (3CaO . SiO2) practically ends after 28 days. (b) The quickest compound in cement to react with water is tri-calcium aluminate (3CaO . Al2O3) (c) For high – strength concrete at a later stage, a high content of C2S (2CaO. SiO2) is used. (d) All of these are correct. 

5.18. For manufacturing quick hardening Portland cement, which one of the following is used? 

(a) C3A (b) C4AF (c) C3S (d) C2S 

5.19. The Portland cement which contains more than (a) 50 to 60% of C3S, is called Alit. (b) 12% of C3A, is called Aluminate (c) 60% of C3S, is called high Alit. (d) 35% of C2S, is called Belit. (e) All of these are correct. 

5.20. The steel rotary kiln used in the process of manufacturing normal setting ordinary Portland cement has: (a) diameter 250 cm to 300 cm   (b) length 90 m to120 m (c) gradient1 in 25 to1 in 30 (d) supports at intervals by masonry or concrete columns. (e) All of these correct.

5.21. A 50 kg cement bag contains: 

(a) 0.035 m3 of cement. (b) 0.025 m3 of cement. (c) 0.033 m3 of cement. (d) None of these. 

5.22. The ratio of the percentages of alumina to that of iron oxide in cement should not be less than. (a) 0.30 (b) 0.33 (c) 0.44 (d) 0.55 (e) 0.66 

5.23. The total sulphur content in cement should not exceed: (a) 1.50% (b) 1.75% (c) 2.50% (d) 2.75% 

5.24. Weight of magnesia in cement should not exceed: 

(a) 2.5% (b) 3.5% (c) 4.00% (d) 5.00% 5.25. An amount of cement weighing100 gm when passed continueusly only for15 minutes through IS sieve No 9 should not retain a residue: (a) 5.0% of the original weight. (b) 7.5% of the original weight (c) 10.0% of the original weight (d) 12.5% of the original weight. 

5.26. The water cement ratio for the cement sand mortar (1:3) is kept. (a) 0.25 (b) 0.30 (c) 0.35 (d) 0.40 

5.27. The compressive strength of the Test Cube at the end of 3 days should not be. 

(a) less than115 kg/cm2 after 3 days and 175 kg/cm2 after 7 days. (b) less than 95 kg/cm2 after 3 days and 160 kg/cm2 after 7 days. (c) less than 80 kg/cm2 after 3 days and 210 kg/ cm2 after 7 days. (d) none of these. 

5.28. The tensile stress of a Test Cube of cement sand ratio1:3. (a) After 3 days should not be less than 20 kg/cm2 and after 7 days. (b) After 3 days not to less than 15 kg/cm2 and after 7 days 20 kg/cm2. (c) After 3 days should not be less than 10 kg/ cm2 and after 7 days 15 kg/cm2. 

5.29.The Vicat apparatus is used for testing: (a) initial setting time of cement. (b) nal setting time of cement. (c) soundness of cement. (d) both (a) and (b) (e) both (b) and (c) 

5.30.The interval of time between the moment of addition of water to cement and commencement of filling the Vicat apparatus mould is known as the time of gauging that should be.

a) 2½ to 3½ minutes. (b) 3 to 4 minutes. (c) 2æ to 4º minutes. (d) None of these correct. 

5.31. In Vicat apparatus. (a) The square needle is used for testing initial setting time. (b) The plunger is used for consistency test. (c) The needle with annular collar is used for testing nal setting time. (d) All of these are correct. 

5.32.The initial setting time of ordinary Portland cement should not be less than: (a) 20 minutes (b) 25 minutes (c) 30 minutes (d) 36 minutes 

5.33.The anal setting time of ordinary port land cement should not be more than. (a) 8 hours (b) 9 hours (c) 10 hours (d) 12 hours 

5.34. The soundness test of cement: (a) is performed with the help of Lechatlier apparatus. (b) is carried out to detect the presence of un-combined lime in cement. (c) the Lechattier apparatus has a brass mould of diameter 30 mm, height 30 mm and thickness 0.5 mm. (d) All of these are correct. 

5.35.The distance between the two readings of the Lechattier apparatus should not exceed: (a) 4 mm (b) 5 mm (c) 7.5 mm (d) 10 mm 

5.36.For the storage of 20 bags (or1 tonne) of cement, minimum storage space is required: (a) 1 m3 (b) ½ m3 (c) 1½ m3 (d) None of these 5.37.An acid resistant cement contains: (a) Aggregates of quartz and quartzites. (b) Sodium uosilicate (Na2SiFe) (c) Soluble glass. (d) All of these. 

5.38.In additive sodium auosilicate in acid resistant cement: (a) accelerates the hardening process of soluble glass. (b) Increases the resistance of cement to acidic water. (c) Both (a) and (b) (d) Neither (a) nor (b) 

5.39.Pick up the correct statement from the following: (a) The binding material of acid-resistant cement is soluble glass (a water solution of sodium silicate or potassime silica). (b) The ratio of the number of silica molecules to that of alkli oxide molecules is known as glass modulus (c) The value of glass modulus varies from 2.50 to 3.50. (d) By adding 0.5 percent linseed oil, the cement resistance to water increases. (e) All of these. 

5.40. The slag which is a waste product obtained in the manufacturing process of pig-iron, contains: (a) Alumina (b) Lime  (c) Silica (d) All of these

5.41. The blast furnace cement 

(a) gains less strength in early days. (b) requires longer curring period. (c) is durable. (d) proves to be economical since it is made from a waste product. (e) All of these. 

5.42. Which one of the following statements is correct? 

(a) The mixing of the chromium oxide to cement gives a green color. (b) The mixing of cobalt to cement imparts blue colour (c) The maganese dioxide when mixed in cement produces black or brown coloured cement. (d) All of these are correct. 

5.43. High alumina cement: (a) contains bauxite not less than 32 percent. (b) must contain alumina by weight to lime in the ratio between 0.85 to1.30. (c) sets quickly and attains higher ultimate strength in a short period. (d) attains strength in a day about 400 kg/cm2 and after 3 days 500 kg/cm2 (e) All of these. 

5.44. Which one of the following is hydrophotric admixture hydrophotic cement? 

(a) Alcohol (b) Napthene soap (c) Oxidized petroline (d) All of these. 

5.45.The low heat cement contains / is used for: 

(a) Lower percentage of tricalcium aluminates (C3A) roughly 5%. (b) Higher percentage dicalcium silicate (C2S) roughly 46%. (c) Mass concrete work such as dams. (d) All of these. 

5.46. Pozzuolana cement: 

(a) is a volcanic powder. (b) resembles surkhi is prepared by burning bricks. (c) contains10 to 30 percentage of pozzuolana materials. (d) All of these. 

5.47. Pick up the correct statement from the following regarding quick setting cement. (a) It contains a small percentage of aluminium sulphate. (b) It contains less percentage of gypsum or retarder. (c) It starts setting within 5 minutes after addition of water and in less than 30 minutes it attains good strength. (d) Fineness of the grinding is responsible for accelerating the setting action of cement. (e) All of these. 5.48. Quick setting cement is usefully used to lay concrete under: (a) static water (b) running water (c) both (a) and (b) (d) neither (a) nor (b)

5.49. The rapid hardening cement: (a) has initial and nal setting times as that of ordinary Portland cement. (b) attains high strength in early days. (c) contains high percentage of tricalcium silicate (C3S) about 56% (d) All of these. 5.50. Sulphate resisting cement is generally used in (a) Canal linings (b) Culverts (c) Systems (d) All of these. 5.51. White cement. (a) is made by raw materials practically free from colouring oxides of iron, manganese, or chromium. (b) is obtained by burning the clinkers by oil fuel. (c) should not set earlier than 30 minutes. (d) All of these. 6. MORTARS 6.1. Pick up the correct statement from the following: (a) The required quantity of water and a mixture of binding material (cement or lime) and ne aggregates (sand) is called mortar. (b) The binding material in mortars is known as matrix. (c) The ne aggregate in mortars is called an adulterant. (d) The matrix binds the particles of the adulterant to provide durability, quality and strength of the mortar. (e) All of these. 6.2. Pick up the correct statement from the following: (a) The strength of a mortar depends on the quantity and quality of matrix. (b) The combined effect of matrix and adultrant of mortar is to bind the bricks or stones rmly. (c) Both (a) and (b) (d) Neither (a) nor (b) 6.3. Pick up the correct statement from the following: (a) The sand forms an important ingredient of mortar. (b) The sand particles consist of small grains of silica (SiO2) (c) The sand is formed by the decomposition of stand stones due to weathering. (d) All of these. 6.4. Pick up the correct statement from the following: (a) The pit-sand consists of sharp angular grains. (b) The pit-sand particles are free from salts. (c) The pit-sand is an excellent material for mortar or concrete. (d) When pit-sand particles are rubbed between ngers do not leave any stain on the ngers. (e) All of these. 6.5. The river bed sand: (a) is obtained from the beds of perennial rivers. (b) contains ne – moulded grains due to mutual attrition under the action of water current. (c) is almost white in colour. d) is widely used for building construction purposes. (e) All of these.

6.6. The sea sand: (a) is abundantly available along sea shore. (b) contains particles of ne rounded shape. (c) contain salts. (d) is seldomly used for engineering purposes. (e) All of these. 6.7. Pick up the correct statement from the following: (a) The presence of moisture in sand increases the sand volume. (b) The moisture in sand causes a lm of water around sand particles which results in the increase of sand volume. (c) The ner the sand particles the more will be the increase in sand volume of given moisture content. (d) The phenomena of the increase of sand volume due to the presence of moisture in sand, is called bulking of sand. (e) All of these. 6.8. Pick up the correct statement from the following: (a) A dry sand and a completed ooded sand with water has practically the same volume. (b) When proper allowance is not made for bulking of sand the cost of concrete and mortar increases. (c) Ignoring the bulking effect of sand results in to under sanded mixes. (d) The under-sanded mixes are harsh and difcult for working and placing. (e) All of these. 6.9. Which one of the following statements is correct? (a) Sand in mortar does not increase the strength of the mortar as it is used only to increase the bulk volume. (b) Sand in mortar prevents excessive shrinkage while drying. (c) Sand in variation of its proportion with cement increases the resistive force against crushing. (d) Sand particles increase the surface area for spreading and adhering of the binding material. (e) All of these. 6.10. Pick up the correct statement from the following: (a) Presence of clay in sand is tested by keeping some quantity of sand in a glass of water containing water and vigorously shaken and allowed to settle. A distinct layer of clay gets formed on the top if there is clay in sand. (b) The presence of salts in sand is detected by tasting. (c) The size and sharpness of grains are examined by touching and observing with eye. (d) All of these. 6.11. Which one of the following is a substitute of sand in mortars. (a) Stone screening. (b) Surkhi (c) Cinder (d) Ashes from coal. (e) All of these.

6.12. In lime mortars: (a) Lime is used as a binding material. (b) The volume of lime is taken 2 to 3 times that of volume of sand. (c) If hydraulic lime is used, the proportion of lime to sand is taken as 1:2. (d) High plasticity is obtained. (e) All of these. 6.13. In surkhi mortar: (a) Surkhi is used instead of sand. (b) Surkhi should conrm to B.I.S. No. 9 sieve. (c) The residue of Surkhi on sieve no. 9 should not be more than 10% by weight. (d) All of these. 6.14. In cement mortar: (a) The proportion of cement to sand by volume varies 1:2 to 1:6 or even more as per the requirement of the strength. (b) Sand can be used as adulterant. (c) High strength and water-resisting properties prevail. (d) All of these are correct. 6.15. Pick up the correct statement from the following: (a) When cement is added to improve the quality of lime mortar, a gauged mortar is obtained. (b) The gauged mortar proves to be economical strong and dense. (c) The normal proportion of cement to lime by volume in the gauged mortar is about 1:6 to 1:8. (d) All of these. 6.16. The gauged mortar is also known: (a) a composite mortar. (b) a lime-cement mortar. (c) a cement clay mortar. (d) All of these. 6.17. The re resistant mortar. (a) is obtained by adding aluminous cement and nely crushed powder ne-bricks. (b) contains a proportion of1 part of aluminous cement and 2 parts of powder of ne-bricks. (c) is used with ne-bricks for lining furnaces, re place etc. (d) All of these are correct. 6.18. Light weight mortar obtained by adding sawdust, wood powder to lime mortar or cement mortar is used for. (a) sound proof constructions. (b) heat proof constructions. (c) both (a) and (b) (d) neither (a) nor (b) 6.19. The packing mortar which is generally used for packing oil wells possesses: (a) High homogeneity. (b) Water resistance. (c) Predetermined setting time (d) formation of solid water proof cracks. (e) All of these.

6.20.Which one the following is a packing mortar? (a) Cement–sand (b) Cement–loam (c) Cement–loam sand (d) All of these are correct 6.21.The sound absorbing mortar used to reduce the noise level contains: (a) Portland cement (b) Lime (c) Gypsum. (d) Slag and light weight porous materials. (e) All of these. 6.22.Which one of the following terms is generally referred to in mortars (a) Mobility (b) Placeability (c) Both (a) and (b) (d) Neither (a) nor (b) 6.23.Which one of the following statements is correct? (a) The lime mortar should be consumed within 36 hours for its preparation. (b) The cement mortar should be consumed within 30 minutes after adding water. (c) The gauged mortar(composite mortar) should be consumed within 2 hours after adding water. (d) All of these are correct. 6.24.Pick up the correct statement from the following: (a) Sea water can be used with hydraulic lime or cement as it prevents too quick drying of mortar. (b) Building units should be soaked in water before mortar is spread over them. (c) The new construction work should be kept damp by sprinkling water to avoid rapid drying of mortar. (d) All of these are correct. 6.25.Pick up the correct statement from the following: (a) For damp proof courses and cement concrete roads, the cement mortar proportion is kept 1:2. (b) For partition walls and parapet walls, cement mortar proportion is kept 1:3. (c) For plaster work, cement proportion is kept1:3 to 1:4. (d) For pointing work, cement proportion is kept 1:1 to 1:2. (e) All of these. 7. TIMBER 7.1. A tree of not less them 60 cm in girth as a building material must possess: (a) Low heat conductivity. (b) Relatively high strength. (c) Small bulk density. (d) A menability to mechanical working. (e) All of these. 7.2. Timber as a building material: (a) is suspectable to decay and inamation? (b) uctuates its properties due to change in moisture content. (c) possesses different strength along length and across ber. (d) All of these

6.20.Which one the following is a packing mortar? (a) Cement–sand (b) Cement–loam (c) Cement–loam sand (d) All of these are correct 6.21.The sound absorbing mortar used to reduce the noise level contains: (a) Portland cement (b) Lime (c) Gypsum. (d) Slag and light weight porous materials. (e) All of these. 6.22.Which one of the following terms is generally referred to in mortars (a) Mobility (b) Placeability (c) Both (a) and (b) (d) Neither (a) nor (b) 6.23.Which one of the following statements is correct? (a) The lime mortar should be consumed within 36 hours for its preparation. (b) The cement mortar should be consumed within 30 minutes after adding water. (c) The gauged mortar(composite mortar) should be consumed within 2 hours after adding water. (d) All of these are correct. 6.24.Pick up the correct statement from the following: (a) Sea water can be used with hydraulic lime or cement as it prevents too quick drying of mortar. (b) Building units should be soaked in water before mortar is spread over them. (c) The new construction work should be kept damp by sprinkling water to avoid rapid drying of mortar. (d) All of these are correct. 6.25.Pick up the correct statement from the following: (a) For damp proof courses and cement concrete roads, the cement mortar proportion is kept 1:2. (b) For partition walls and parapet walls, cement mortar proportion is kept 1:3. (c) For plaster work, cement proportion is kept1:3 to 1:4. (d) For pointing work, cement proportion is kept 1:1 to 1:2. (e) All of these. 7. TIMBER 7.1. A tree of not less them 60 cm in girth as a building material must possess: (a) Low heat conductivity. (b) Relatively high strength. (c) Small bulk density. (d) A menability to mechanical working. (e) All of these. 7.2. Timber as a building material: (a) is suspectable to decay and inamation? (b) uctuates its properties due to change in moisture content. (c) possesses different strength along length and across ber. (d) All of these

7.12. Cambium layer of tree trunk: (a) is a thin layer of sap between sap wood and inner bark. (b) contains pure sap. (c) gets exposed by removing the tree bark. (d) All of these. 7.13. Medullary rays in the tree trunk: (a) are thin radial bers extending form faith to cambium layer. (b) hold together the annual rings of heart wood and sap wood. (c) both (a) and (b) (d) neither (a) nor (b) 7.14. Living cell of a tree consists of: (a) a membrane (b) proto plasma. (c) Sap (d) Core (e) All of these 7.15. The protoplasm in a living cell is a granular, trans- parent, viscous vegetable protein composed of: (a) Carbon (b) Hydrogen (c) Oxygen (d) Nitrogen (e) All of these 7.16.The core of a living cell of a tree contains: (a) Phosphorus (b) Sulphur (c) Magnessium (d) None of these 7.17. Which one of the following cells usually found in medullary ray: (a) Conductive cells (b) Mechanical cells (c) Storage cells (d) None of these 7.18. Pick up the correct statement from the following: (a) The durability of timber obtained from immatured trees is less. (b) The tree felled after attaining its maturity provides decayed timber. (c) The age of good trees for felling is 50 to100 years. (d) All of these. 7.19. Pick up the correct statement from the following: (a) The equilibrium formula of applied mechanics is applied for felling a matured tree. (b) The timber from a freshly felled tree should be sown after removing the bark. (c) Proper wedges should be driven gradually into the felling tree to cause smooth felling of the tree. (d) All of these. 7.20. Which one of the following statements is correct? (a) The felling of trees in autumn and spring when sap remains in vigorous motion is not recommended. (b) In hilly regions felling of trees should be resorted to the mid-summer. (c) In plains, the mid-winter is suitable time for felling trees. (d) All of these are correct.

7.21.The decay of wood due to fungi occurs: (a) when the moisture content of timber is above 20 percent. (b) when there is presence of air and warmth for tree growth of fungi. (c) both (a) and (b) (d) neither (a) nor (b) 7.22.Which one of the following defects is caused in timbers by the fungi? (a) Wet rot (b) Dry rot (c) Write rot (d) Heart rot (e) All of these. 7.23. Pick up the correct statement from the following: (a) Conversion of wood by the attack of fungi into clay-powder form is called dry rot defect. (b) The dry rot occurs in improperly ventilated basements, damp places as kitchen and toilets. (c) The dry rot attacks unseasoned soft woods and sap wood. (d) The fungus grows rapidly in the absence of sunlight, dampness presence of sap, stagnant air coupled with warmth. (e) All of these. 7.24. After removing the damaged portion of dry rot, the remaining unaffected portion should be painted with. (a) a solution of copper sulphate. (b) a solution of dilute hydrochloric acid. (c) a solution of nitric acid (d) None of these. 7.25.Pick up the correct statement from the following: (a) Heart-rot is formed when it is exposed to the attack of atmosphere agents. (b) The wet rot converts timber into greyish brown powder. (c) For the prevention of wet rot, a well seasoned timber should be used for exterior work or for underground work the timber to be pointed for protection against moisture. (d) All of these are correct. 7.26.Pick up the correct statement from the following: (a) The timber decayed by beetles (small insects) get converted into our-like powder (b) To the timber attacked by beetles looks sound till it completely fails. (c) The wood attacked by marine bores loses colour and strength. (d) Termites eat away the wood from the core of the cross-section. (e) All of these are correct. 7.27.Pick up the correct statement from the following: (a) The portion of the tree trunk from which a branch is removed, continuous to be nourished from the stem from a pretty long time and ultimately results in the formation of knot. (b) The pin-knot is formed if diameter is up to 6.50 mm (c) The peculiar curved swettings found on the body of a free are called rind galls. (d) The rind galls get developed at points from where branches are improperly removed. (e) All of these. 

7.28. The curved cracks which separate partly one annual ring from the other are called: (a) Cup shakes (b) Heart shakes (c) Ring shakes (d) Radial shakes (e) Star shakes 7.29.The cracks which extend from the pith to sapwood in the direction of medullary rays are called: (a) Cup shakes (b) Heart shakes (c) Ring shakes (d) Radial shakes (e) Star shakes 7.30.The cracks in the form of cup shakes which cover the entire annual ring are called: (a) Heart shakes (b) Ring shakes (c) Radial shakes (d) Star shakes 7.31. The cracks in the cross-section of timber which extend from bark towards the sapwood are called: (a) Ring shakes (b) Star shakes (c) Heart shakes (d) Cup shakes 7.32. Radial shakes in the timber cross-section : (a) are similar to starshakes (b) radiate a short distance from the bark towards the centre (c) follow the direction of annual ring and ultimately run towards the pith (d) All of these are correct 7.33. The sound conductivity in timber: (a) is faster along the ber (b) is lower in radial direction (c) is slowest along the core of the cross-section. (d) All of these. 7.34. A good preservate affectively penetrates at least for a depth of (a) 6 mm to 8 mm (b) 8 mm to12 mm (c) 6 mm to16 mm (d) 6 mm to 25 mm 7.35. ASCU preservative for timber contains by weight: (a) 1 part of hydrated arsenicpentoxide (AS2O5 . 2H2O) (b) 3 parts of blue vitriol (copper sulphate) (C4SO4 . 5H2O) (c) 4 parts of potassium dichromate (K2Cr2O4) or sodium dichromate (Na2Cr2O7 . 2H2O) (d) All of these 7.36. ASCU preservative: (a) is available in powder form (b) 6 parts by weight of ASCU and two parts by weight of water are mixed to prepare the ASCU solution (c) gives timber protection against the attack of white ants (d) solution is odourless (e) All of these are correct.

7.37.Which one of the following is water borne preservatives? (a) Copper sulphate (b) Mercury chloride (c) Sodium uorides (d) Zinc chloride (e) All of these 7.38. The coal tar: (a) is applied on the timber surface with hot coal tar with the help of a brush (b) has unpleasant smell and appearance (c) makes timber unsuitable for painting but it is re resistant (d) is found to be most useful for timber embedded in ground (e) All of these. 7.39.In the process of creosotting a timber (a) the creosote oil is pumped in the chamber containing thoroughly seasoned and dried timber (b) timber is taken out of the chamber when it absorbs creosote oil (c) the creosote oil used, is one of the best antiseptic for the timber against wood attacking fungi. (d) causes an unpleasant odour. (e) All of these. 7.40. The oil paints: (a) should be coated on well seasoned timber (b) preserve timber from mixture (c) make timber durable (d) All of these. 7.41. To preserve timber from white ants, which one of the following is most suitable? (a) Ascu treatment (b) Coal tar treatment (c) Creosote oil (d) Solignum paints 7.42. Which one of the following is refractory timber? (a) Sal (b) Teak (c) Deodar (d) None of these 7.43. To make the timber re resistant, anti-pyrites are used which contains: (a) Salts of ammonium (b) Boric salts (c) Phosphoric acids (d) All of these 7.44. Sir Abel’s process for making timbers re-resistant, the sequence of the application of the chemicals is: (a) Dilute solution of sodium silicate → cream like paste of slaked fat lime → concentrated solution of silicate of soda (b) Cream like paste of slaked fat lime → concentrated solution of silicate of soda → dilute solution of sodium silicate (c) Concentrated solution of silicate of soda → dilute solution of sodium silicate → cream like paste of slaked fat lime. (d) None of these 7.45.Pick up the correct statement from the following: (a) The process of drying of timber is known as seasoning of timber. (b) Irregular drying of timber during seasoning causesshrinkage and sets up stresses between the bers (c) Timber warps and shakes get developed in timber. (d) All of these