MCQOPTIONS
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MCQOPTIONS
This section includes 8247 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 201. |
Hollow refractory bricks are made by |
| A. | slip casting |
| B. | hand moulding |
| C. | pressing/machine moulding |
| D. | extrusion |
| Answer» B. hand moulding | |
| 202. |
Quartz is |
| A. | stable form of silica upto 870 C. |
| B. | converted to tridymite on firing between 870 to 1470 C. |
| C. | transformed to crystoballite on heating above 1470 C. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 203. |
Skull is not formed on the carbon blocks in the hearth of a blast furnace, when it becomes cold, becaus of its |
| A. | non-wetting characteristic. |
| B. | high thermal conductivity. |
| C. | high crushing strength. |
| D. | none of these. |
| Answer» B. high thermal conductivity. | |
| 204. |
Pyrometric cone equivalent (PCE) of a refractory is the measure of its |
| A. | spalling resistance. |
| B. | fusion point. |
| C. | resistance to slag penetration. |
| D. | resistance to carbon monoxide attack. |
| Answer» C. resistance to slag penetration. | |
| 205. |
Bauxite calcining rotary kilns are lined with __________ bricks. |
| A. | fireclay |
| B. | carbon |
| C. | 85% alumina |
| D. | corundum |
| Answer» D. corundum | |
| 206. |
Silica refractories are not used in |
| A. | coke oven walls. |
| B. | beehive coke ovens. |
| C. | dome and upper portion of B.F. stoves. |
| D. | open hearth furnace roof. |
| Answer» C. dome and upper portion of B.F. stoves. | |
| 207. |
Refractory materials are never used in the construction of |
| A. | segar cones |
| B. | orton cones |
| C. | pressure vessels |
| D. | ovens & retorts |
| Answer» D. ovens & retorts | |
| 208. |
Segar cones are used for the determination of __________ of refractories. |
| A. | softening temperature |
| B. | spalling resistance |
| C. | electrical conductivity |
| D. | resistance to slag attack |
| Answer» B. spalling resistance | |
| 209. |
Carbon refractories have very high |
| A. | wetting characteristics |
| B. | refractoriness |
| C. | thermal conductivity |
| D. | both (b) and (c) |
| Answer» E. | |
| 210. |
Sillimanite is a __________ refractory. |
| A. | basic |
| B. | neutral |
| C. | high alumina |
| D. | insulating |
| Answer» D. insulating | |
| 211. |
High refractorinness of refractory bricks means, that it has a |
| A. | high spalling resistance. |
| B. | low spalling resistance. |
| C. | high resistance to fusion. |
| D. | low porosity. |
| Answer» D. low porosity. | |
| 212. |
Conversion of silica mineral to cristobalite is accompanied by reduction in its |
| A. | volume |
| B. | specific gravity |
| C. | both (a) & (b) |
| D. | neither (a) nor (b) |
| Answer» C. both (a) & (b) | |
| 213. |
Chrome magnesite is not used in the |
| A. | inner lining of L.D. converter. |
| B. | aluminium melting furnaces. |
| C. | wear out lining of steel melting furnaces. |
| D. | all (a), and (b) and (c) |
| Answer» D. all (a), and (b) and (c) | |
| 214. |
Which of the following bricks has the most close values of RUL and PCE ? |
| A. | Silica bricks |
| B. | Fireclay bricks |
| C. | High alumina bricks |
| D. | Tar dolomite bricks |
| Answer» B. Fireclay bricks | |
| 215. |
Tar dolomite bricks are used in the |
| A. | basic Bessemer converter |
| B. | basic open hearth furnace |
| C. | electric furnaces |
| D. | all (a), (b) and (c) |
| Answer» E. | |
| 216. |
Which furnace consumes maximum refractory annually in an integrated steel plant ? |
| A. | Soaking pit |
| B. | Blastfurnace |
| C. | L.D. converter |
| D. | Coke ovens |
| Answer» D. Coke ovens | |
| 217. |
Lower part of hot metal mixer are lined with __________ bricks. |
| A. | superduty fireclay |
| B. | high alumina |
| C. | silica |
| D. | carborundum |
| Answer» E. | |
| 218. |
An indication of degree of firing in silica brick is its |
| A. | specific gravity |
| B. | fusion point |
| C. | RUL |
| D. | none of these |
| Answer» B. fusion point | |
| 219. |
Vacuum steel degassing units are lined with |
| A. | silica bricks |
| B. | low duty firebricks |
| C. | high alumina bricks |
| D. | graphite blocks |
| Answer» D. graphite blocks | |
| 220. |
The main raw material for manufacture of silicon carbide refractories is |
| A. | corrundum |
| B. | carborundum |
| C. | bauxite |
| D. | periclase |
| Answer» C. bauxite | |
| 221. |
Chromite refractories are used in |
| A. | bottom of soaking pits. |
| B. | between acid & basic linings in basic open hearth furnaces to prevent their chemical action with each other. |
| C. | both (a) & (b) |
| D. | neither (a) and (b) |
| Answer» D. neither (a) and (b) | |
| 222. |
Which of the following has the lowest electrical resistivity ? |
| A. | Graphite |
| B. | Fireclay |
| C. | Alumina |
| D. | Zircon |
| Answer» B. Fireclay | |
| 223. |
Silica bricks have low spalling resistance below 600 C, due to its |
| A. | very high thermal conductivity. |
| B. | high co-efficient of expansion upto this temperature. |
| C. | high thermal diffusivity. |
| D. | low refractoriness. |
| Answer» C. high thermal diffusivity. | |
| 224. |
Spalling of a refractory means its |
| A. | softening. |
| B. | fracture due to uneven expansion at high temperature. |
| C. | resistancce to compressive loads. |
| D. | resistance to chemical action of gases and molten fluxes. |
| Answer» C. resistancce to compressive loads. | |
| 225. |
Carbon refractories are exclusively used in the |
| A. | hearth of blast furnace. |
| B. | walls of coke oven. |
| C. | regenerators of coke oven. |
| D. | side wall of soaking pits. |
| Answer» B. walls of coke oven. | |
| 226. |
Spalling tendency of refractories is reduced by increasing its |
| A. | porosity |
| B. | specific gravity |
| C. | thermal conductivity |
| D. | strength |
| Answer» B. specific gravity | |
| 227. |
Dry mix hydraulic compositions of refractory aggregates with suitable bonding materials are called refractory |
| A. | mortars |
| B. | cements |
| C. | castables |
| D. | none of these |
| Answer» D. none of these | |
| 228. |
Bottom of basic open hearth furnace are constructed of |
| A. | dead burnt magnesite ramming mass. |
| B. | porous fireclay bricks. |
| C. | semi-silica bricks. |
| D. | silicon carbide bricks. |
| Answer» B. porous fireclay bricks. | |
| 229. |
Lower wall courses of soaking pits are made of __________ bricks to avoid the action of molten slag & scale. |
| A. | chrome or magnesite |
| B. | silicon carbide |
| C. | silica |
| D. | lowduty fireclay |
| Answer» B. silicon carbide | |
| 230. |
Addition of grog in fireclay brick during its manufacture is advantageous, because it results in |
| A. | less shrinkage in heating, decreased apparent porosity & increased specific gravity. |
| B. | high strength & thermal spalling resistance. |
| C. | less addition of water to get a workable plasticity & lesser time required for drying the raw refractories and hence increased rate of production. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 231. |
Slide gates in teeming laddie used for steel pouring in ingot moulds is lined with __________ bricks. |
| A. | bakelite impregnated or fused periclase |
| B. | silica |
| C. | semi-silica |
| D. | fireclay |
| Answer» B. silica | |
| 232. |
Which form of silica has the highest specific gravity ? |
| A. | Quartz |
| B. | Cristobalite |
| C. | Tridymite |
| D. | All have the same specific gravity |
| Answer» B. Cristobalite | |
| 233. |
Ceramic recuperators used for waste heat recovery from high temperature flue gas going out of the furnace is made of |
| A. | fireclay |
| B. | silicon carbide |
| C. | corrundum |
| D. | siliceous fireclay |
| Answer» C. corrundum | |
| 234. |
__________ is the measure of the strength of refractory under the combined effect of temperature & load. |
| A. | Porosity |
| B. | RUL |
| C. | Specific gravity |
| D. | Thermal conductivity |
| Answer» C. Specific gravity | |
| 235. |
Crushing strength of a refractory |
| A. | increases with rise in service temperature. |
| B. | decreases with rise in service temperature. |
| C. | is unaffected with change in service temperature. |
| D. | decreases with increase in porosity. |
| Answer» C. is unaffected with change in service temperature. | |
| 236. |
Fireclay bricks are not used in the |
| A. | blast furnace |
| B. | hot blast stove |
| C. | cupola |
| D. | wall of coke oven |
| Answer» E. | |
| 237. |
Ramming masses are used for |
| A. | obtaining monolithic working faces. |
| B. | repairing construction of various furnace parts. |
| C. | both (a) & (b). |
| D. | neither (a) nor (b). |
| Answer» D. neither (a) nor (b). | |
| 238. |
In panel test for spalling resistance, the average face temperature of panel assembly is maintained at __________ C for 24 hours. |
| A. | 700 |
| B. | 1000 |
| C. | 1600 |
| D. | 2000 |
| Answer» D. 2000 | |
| 239. |
Refractories used in/for __________ should have low thermal conductivity. |
| A. | coke ovens |
| B. | insulation |
| C. | regenerators |
| D. | muffle furnaces |
| Answer» C. regenerators | |
| 240. |
10 to 30% magnesite is added to chromite to produce chrome-magnesite refractories. Magnesite addition is mainly done to improve the __________ of chromite. |
| A. | spalling resistance |
| B. | refractoriness |
| C. | crushing strength |
| D. | resistance to slag |
| Answer» B. refractoriness | |
| 241. |
Which is not a natural insulating material? |
| A. | Diatomaceous earth/kieselgur |
| B. | Asbestos |
| C. | Vermiculite |
| D. | None of these |
| Answer» E. | |
| 242. |
Magnesite refractories are generally not used in the |
| A. | electric furnace walls. |
| B. | steel melting furnace. |
| C. | open hearth furnace. |
| D. | burning zone of cement kilns. |
| Answer» C. open hearth furnace. | |
| 243. |
Rotary kilns meant for calcination of limestone are lined with chrome magnesite in __________ zone. |
| A. | preheating |
| B. | cooling |
| C. | burning |
| D. | all |
| Answer» D. all | |
| 244. |
Which is not an acidic refractory ? |
| A. | Silica |
| B. | Fireclay |
| C. | High alumina refractory |
| D. | Carbon black |
| Answer» E. | |
| 245. |
Natural silica |
| A. | mainly contains quartz. |
| B. | is not stable at high temperature. |
| C. | transforms to other allotropic forms i.e tridymite and cristoballite involving very high volume changes. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 246. |
Thermal conductivity of refractory bricks |
| A. | increases with decrease in porosity. |
| B. | decreases with decreases in porosity. |
| C. | is independent of its porosity and is maximum for insulating bricks. |
| D. | increases with the amount of air entrapped in pores. |
| Answer» B. decreases with decreases in porosity. | |
| 247. |
Which of the following bricks should not be used, if the furnace is to be used intermit-tantly ? |
| A. | Firebricks |
| B. | Silica bricks |
| C. | Silicon carbide bricks |
| D. | Sillimanite |
| Answer» C. Silicon carbide bricks | |
| 248. |
Upper portion of hot metal mixer are lined with mullite bricks, which helps in resisting the |
| A. | washing action of metal. |
| B. | corrosion by layer of slag. |
| C. | both (a) & (b). |
| D. | neither (a) nor (b). |
| Answer» B. corrosion by layer of slag. | |
| 249. |
Grog addition in fireclay during brick manufacture is done to |
| A. | reduce its shrinkage on heating. |
| B. | impart greater spalling resistance. |
| C. | enhance the strength of fired refractories. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 250. |
Zirconia refractories are not used in |
| A. | making sheaths for thermocouple. |
| B. | lining high temperature ceramic kilns. |
| C. | furnaces subjected to fluctuating temperature. |
| D. | high frequency induction furnaces in the form of inductors. |
| Answer» D. high frequency induction furnaces in the form of inductors. | |