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Correct choice is (a) 0.60

Easiest EXPLANATION: For a GOOD stone, the percentage absorption by WEIGHT after a day in the water absorption test should not exceed 0.60. Also, the SPECIFIC gravity should be greater than 2.7 for good building stone.

The correct choice is (c) It is cheaper than BLASTING powder

Easy EXPLANATION: DYNAMITE is an explosive USED in the blasting process. It is very strong and can be used for quarrying under water as well. It does not need hard tamping. It is much costlier than the blasting powder.

Right OPTION is (c) SALTS of calcium or ammonia

The explanation is: Absorbents like salts of calcium or ammonia are capable of absorbing EXCESS moisture from the air. However, the adsorbents like silica gel and activated alumina allow moisture to STAY only at the surface.

The correct option is (d) OCTAGONAL

For EXPLANATION: AUGITE is a mineral found in igneous ROCKS and resembles hornblende. Augite forms octagonal crystals and changes to CHLORITE by hydration.

The correct choice is (a) ARGILLACEOUS rocks

Easy explanation: Clay PREDOMINATES in argillaceous rocks. Slate is an EXAMPLE of this type of rock. In CALCAREOUS rocks, calcium carbonate predominates while in SILICEOUS rocks, silica predominates.

Right CHOICE is (c) Cupola furnace

Explanation: Remelting of pig iron with limestone and COKE to MANUFACTURE cast iron is carried out in a cupola furnace. It has a smaller size than the BLAST furnace and its SHAPE is cylindrical.

Correct choice is (c) 1000 KG per cm^2

For explanation I would say: Crushing strength should be greater than 1000 kg per cm^2 for a good structural STONE. Crushing strength of BASALT is as large as 1500 to 1900 kg per cm^2 while that of limestone and sandstone is 550 and 650 kg per cm^2 respectively.

Right ANSWER is (d) THERMAL resistivity

The best EXPLANATION: The RECIPROCAL of thermal conductivity is known as thermal resistivity. It is given by 1/k. Its units are (mK)/W.

Right choice is (a) FAN coil UNIT

To elaborate: In the chilled water SYSTEM, the return air and the FRESH air mixture is filtered in the fan coil unit. Here, in addition to FILTRATION, the mixture is cooled and dehumidified. After this, it is distributed to the conditioned space through ducting and grills.

Right option is (b) Magnetite

The best I can explain: Magnetite is the black OXIDE of iron. Magnetite is the richest iron ore and CONTAINS about 70-73 % of the iron in its PURE state. It is AVAILABLE in Madras in INDIA.

Right choice is (c) Silicon and manganese

The explanation is: Small AMOUNTS of silicon and manganese improve the quality of BESSEMER pig. HOWEVER, it should be free from phosphorus, COPPER and sulphur.

Right answer is (d) Scraping SPOON

To EXPLAIN: Scraping spoon is USED to remove dust from blast holes in the process of blasting. A tamping bar is used to RAM the material while refilling the blast holes.

Correct choice is (b) 2.5 cm thick LAYER of coconut PITCH CEMENT concrete

Explanation: Thermal insulation of roofs can be obtained by COVERING the top exposed surface of the ROOF with 2.5 cm thick layer of coconut pitch cement concrete. Coconut pitch cement concrete is prepared by mixing coconut pitch with water and cement.

The correct choice is (b) Dry filter

The explanation is: Filters used in AIR conditioning system are of various types. There are viscous type filters, dry filters, spray WASHERS and electric precipitators. A dry filter is made of cloth such as FLANNEL, that is DISCARDED on getting dirty.

Right ANSWER is (a) Thermal conductivity

To explain I WOULD SAY: The amount of heat flow through a unit area of material of unit thickness in one hour, when the temperature difference is maintained at 1°C is known as the thermal conductivity. It is denoted by k. Its units are W/(mK).

Correct option is (a) Hearth

The best explanation: Hearth is the LOWEST part of the blast furnace. It is also known as the crucible. This PORTION of the furnace is used to COLLECT slag and MOLTEN iron.

The CORRECT CHOICE is (b) It should allow moisture to penetrate the surface of the stone

Explanation: An IDEAL preservative used for the preservation of stones should be HIGHLY economical. It should be harmless and non-corrosive. It should not allow moisture to penetrate the surface of the stone.

The CORRECT OPTION is (d) It can be USED for delicate castings

Best explanation: White cast iron has a silvery-white COLOUR and is quite hard. It melts with great DIFFICULTY and cannot be used for delicate castings.

Right CHOICE is (d) Ferrum

Explanation: Latin WORD for iron is Ferrum. It is CHEMICALLY denoted as Fe. METALS are GROUPED into two categories – ferrous metals and non-ferrous metals. Ferrous metals consist of iron as their main constituent while non-ferrous metals do not consist of iron as the main constituent.

The CORRECT option is (b) VOLCANIC

Explanation: Basalt is an example of volcanic rock. These rocks are FORMED DUE to the pouring of magma and the surface of the earth. The cooling is very rapid and this TYPE of rocks possess finely grained structure.

The CORRECT choice is (d) Dust particles get attached to the positive electrode

The best I can explain: Electric precipitators are used to REMOVE dust by providing a strong electric field. In an electric precipitator, the dust particles get attached to the negative electrode. Their INITIAL INSTALLATION cost is HIGH but their operational cost is low.

The correct option is (d) The external supply of air is essential in this type of furnace

To EXPLAIN: Electric REDUCTION furnace is adopted at PLACES where electric power can be cheaply generated. In this, less amount of fluxing MATERIAL is needed and less amount of SLAG is formed. The external supply of air is not essential in this type of furnace.

Correct ANSWER is (b) Pink pig

The explanation: The various varieties of pig iron are Bessemer pig, MOTTLED pig, WHITE pig and grey pig. Mottled pig lies somewhere between the white pig and grey pig. Bessemer pig is obtained from HAEMATITE ores.

Correct choice is (a) True

For EXPLANATION: Dragged finish is suitable for only soft stones. In this, a drag or a comb is rubbed on the surface in all directions. A comb is a piece of steel with a NUMBER of TEETH.

Right answer is (a) Smelting

Best explanation: The VARIOUS methods of quarrying are digging, heating, wedging and blasting. Before actually starting the QUARRY, it should be kept in MIND to carefully examine the exposed surface of rock bed and it is essential to prepare a complete layout of different STAGES involved in the quarrying process.

Right ANSWER is (a) 2%

To explain I would say: In attrition test used to find the RATE of WEAR of stones, wear should be equal to or less than 2 % for GOOD BUILDING stone. If the wear is more than 3%, then the stone is not satisfactory.

The correct option is (a) Haematite

Best EXPLANATION: Haematite is the red oxide of iron. It CONTAINS about 65-70 % of the iron in its pure state. It is AVAILABLE in the state of Madhya PRADESH in India.

The CORRECT answer is (c) CALCAREOUS ROCKS

To explain: According to PHYSICAL classification, rocks are divided into three types. These are STRATIFIED rocks, unstratified rocks and foliated rocks. Physical classification of rocks is based on their general structure. Calcareous rock is a type of rock based on chemical classification.

Right answer is (a) Conduction

The best explanation: The PROCESS of direct transmission of heat through a material is KNOWN as conduction. The amount of heat transfer by this process DEPENDS on various factors LIKE temperature difference, the conductivity of the MEDIUM, the time for which the flow takes place etc.