MCQOPTIONS
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MCQOPTIONS
This section includes 568 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 401. |
Magnesite chrome refractories |
| A. | have better spalling resistance than chrome magnesite refractories. |
| B. | have very low thermal co-efficient of expansion. |
| C. | are not at all resistant to the corrosive action of iron oxide. |
| D. | have very low (50 kg/cm2 ) cold crushing strength (C.C.S.), and can not be used in metalcase form. |
| Answer» B. have very low thermal co-efficient of expansion. | |
| 402. |
Which one contains minimum percentage of SiO2? |
| A. | Firebrick |
| B. | Sillimanite |
| C. | Semi-silica |
| D. | Aluminous firebrick |
| Answer» C. Semi-silica | |
| 403. |
Zircon refractories have |
| A. | low co-efficient of expansion. |
| B. | high RUL (1600°C) and refractoriness (> 2000°C). |
| C. | high spalling resistance. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 404. |
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. | |
| 405. |
Refractory castables are used for |
| A. | producing monolithic linings. |
| B. | patch work. |
| C. | minimising the number of joints in the structure. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 406. |
Cold crushing strength of a refractory does not depend upon its |
| A. | shape |
| B. | composition |
| C. | firing temperature |
| D. | texture |
| Answer» B. composition | |
| 407. |
Fireclay refractories have |
| A. | low co-efficient of thermal expansion. |
| B. | poor thermal spalling resistance. |
| C. | tendency to expand unduly high during firing. |
| D. | very high cost. |
| Answer» B. poor thermal spalling resistance. | |
| 408. |
Fusion temperature of pure silica (SiO2) is __________ °C.$ |
| A. | 1350 |
| B. | 1715 |
| C. | 2570 |
| D. | 2800 |
| Answer» C. 2570 | |
| 409. |
Lower part of hot metal mixer are lined with __________ bricks. |
| A. | superduty fireclay |
| B. | high alumina |
| C. | silica |
| D. | carborundum |
| Answer» E. | |
| 410. |
Chrome magnesite bricks are |
| A. | acidic in nature. |
| B. | neutral in nature. |
| C. | having higher RUL than silica bricks. |
| D. | made by mixing 30% chromite and 70% periclase. |
| Answer» D. made by mixing 30% chromite and 70% periclase. | |
| 411. |
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. | |
| 412. |
Use of higher percentage of lime for bonding silica bricks, reduces their |
| A. | strength |
| B. | abrasion resistance |
| C. | both (a) & (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 413. |
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. | |
| 414. |
Refractories subjected to alternate cycles of heating & cooling are liable to loose their resistance to |
| A. | thermal spalling |
| B. | slag attack |
| C. | fusion under load |
| D. | CO attack |
| Answer» B. slag attack | |
| 415. |
Electrical resistor bars are made of |
| A. | silicon carbide |
| B. | alumina |
| C. | zirconia |
| D. | graphite |
| Answer» B. alumina | |
| 416. |
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 | |
| 417. |
Cermets are |
| A. | composite material containing both ceramic & metallic constituents. |
| B. | having high strength & resistance to high temperature. |
| C. | used in space vehicles, missiles & nuclear energy plants. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 418. |
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 | |
| 419. |
With increase in the density of silica refractories, its |
| A. | resistance to slag attack increases. |
| B. | spalling resistance reduces. |
| C. | both (a) and (b). |
| D. | neither (a) nor (b). |
| Answer» D. neither (a) nor (b). | |
| 420. |
Which of the following is not a neutral refractory ? |
| A. | Silicon carbide |
| B. | Magnesite |
| C. | Chromite |
| D. | Graphite |
| Answer» C. Chromite | |
| 421. |
Dilatometer is used for the determination of __________ of refractories. |
| A. | modulus of rupture |
| B. | permanent linear change |
| C. | resistance to CO attack |
| D. | RUL |
| Answer» C. resistance to CO attack | |
| 422. |
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. | |
| 423. |
Bauxite calcining rotary kilns are lined with __________ bricks. |
| A. | fireclay |
| B. | carbon |
| C. | 85% alumina |
| D. | corundum |
| Answer» D. corundum | |
| 424. |
Colour of fireclay bricks is |
| A. | light buff to reddish buff |
| B. | yellow |
| C. | black |
| D. | none of these |
| Answer» B. yellow | |
| 425. |
Which is not an alumino-silicate refractory? |
| A. | Fireclay bricks. |
| B. | Mullite bricks. |
| C. | Tar dolomite bricks. |
| D. | High alumina bricks. |
| Answer» D. High alumina bricks. | |
| 426. |
Which of the following does not occur during firing/burning of refractories ? |
| A. | Removal of water of hydration. |
| B. | Vitrification. |
| C. | Decrease in crushing strength. |
| D. | Development of stable mineral form. |
| Answer» D. Development of stable mineral form. | |
| 427. |
SiO2 percentage in firebrick is about |
| A. | 35-40 |
| B. | 55-60 |
| C. | 80-85 |
| D. | >94 |
| Answer» C. 80-85 | |
| 428. |
Carborundum used for making crucibles for melting non-ferrous metals is chemically |
| A. | silicon carbide |
| B. | silicon nitride |
| C. | crystalline magnesia |
| D. | zirconium sulphate |
| Answer» B. silicon nitride | |
| 429. |
Carbon refractories |
| A. | do not burn/oxidise, when exposed to air on heating. |
| B. | are not attacked by slags, as they are not wetted by melts. |
| C. | do not resist temperature fluctuations. |
| D. | have extremely low thermal & electrical conductivities. |
| Answer» C. do not resist temperature fluctuations. | |
| 430. |
The maximum linear expansion of silica bricks during firing is about __________ percent. |
| A. | 0.5 |
| B. | 1 |
| C. | 2 |
| D. | 3.5 |
| Answer» E. | |
| 431. |
Magnesite refractories have low resistance to |
| A. | attack by basic slag. |
| B. | abrasion. |
| C. | disintegration on sudden change of temperature. |
| D. | both (b) and (c). |
| Answer» E. | |
| 432. |
Which is not an acidic refractory ? |
| A. | Silica |
| B. | Fireclay |
| C. | High alumina refractory |
| D. | Carbon black |
| Answer» E. | |
| 433. |
PCE value (Segar cone) of superduty refractories is more than 33, which is equivalent to a temperature of __________ °C.$ |
| A. | 1520 |
| B. | 1630 |
| C. | 1670 |
| D. | 1730 |
| Answer» E. | |
| 434. |
Spalling tendency of refractories is reduced by increasing its |
| A. | porosity |
| B. | specific gravity |
| C. | thermal conductivity |
| D. | strength |
| Answer» B. specific gravity | |
| 435. |
Silica refractories |
| A. | crack when subjected to sudden change of temperature. |
| B. | can not be used in the dome of hot blast stoves. |
| C. | have lower thermal conductivity than fireclay bricks. |
| D. | all (a), (b) and (c) |
| Answer» B. can not be used in the dome of hot blast stoves. | |
| 436. |
Rate of slag attack on refractories increases with rise in temperature due to the |
| A. | decreased viscosity of slag. |
| B. | increased thermal conductivity of brick. |
| C. | oxidising condition in the furnace. |
| D. | none of these. |
| Answer» B. increased thermal conductivity of brick. | |
| 437. |
__________ bricks should not be used in oxidising atmosphere. |
| A. | Tar dolomite |
| B. | Carbon |
| C. | Silica |
| D. | Fireclay |
| Answer» C. Silica | |
| 438. |
Roof of a basic open hearth furnace is lined with __________ bricks. |
| A. | silica |
| B. | fireclay |
| C. | dolomite |
| D. | magnesite |
| Answer» B. fireclay | |
| 439. |
With increasing alumina content, the fusion point of high alumina refractories |
| A. | increases. |
| B. | decreases. |
| C. | remains constant. |
| D. | may increase or decrease ; depends on its alumina content. |
| Answer» B. decreases. | |
| 440. |
Alumina-graphite bricks are used for lining the |
| A. | slide gate in teeming laddies. |
| B. | continuous casting systems. |
| C. | both (a) and (b). |
| D. | neither (a) nor (b). |
| Answer» D. neither (a) nor (b). | |
| 441. |
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. | |
| 442. |
Which property is important for bricks used in the combustion chamber & dome of blast furnace stoves ? |
| A. | High refractoriness. |
| B. | High resistance to spalling. |
| C. | High strength and density. |
| D. | All (a), (b) and (c). |
| Answer» B. High resistance to spalling. | |
| 443. |
Dolomite bricks have good resistance to attack by |
| A. | molten steel |
| B. | iron oxide |
| C. | lime slag |
| D. | none of these |
| Answer» B. iron oxide | |
| 444. |
Because of its very high refractoriness of the order of __________ °C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns.$ |
| A. | 1800 |
| B. | 2200 |
| C. | 2400 |
| D. | 2700 |
| Answer» E. | |
| 445. |
High alumina refractories are used in the |
| A. | dome of blast furnace stoves. |
| B. | electric arc furnace roof. |
| C. | glass melting furnaces. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 446. |
__________ of carbon blocks in the hearth of blast furnace helps in avoiding skull formation, when it becomes cold. |
| A. | High thermal conductivity |
| B. | Low porosity |
| C. | Non-wetting characteristics |
| D. | High density |
| Answer» D. High density | |
| 447. |
Refractoriness under load (RUL) is the most important property for the refractory bricks |
| A. | at the hearth bottom of the furnace on which stock is placed. |
| B. | used for furnace insulation. |
| C. | used in the roof of the furnace. |
| D. | none of these. |
| Answer» B. used for furnace insulation. | |
| 448. |
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 | |
| 449. |
Insulating refractories should have |
| A. | high porosity |
| B. | low thermal conductivity |
| C. | both (a) and (b) |
| D. | neither (a) not (b) |
| Answer» C. both (a) and (b) | |
| 450. |
Maximum apparent porosity of magnesite bricks is about __________ percent. |
| A. | 8 |
| B. | 24 |
| C. | 44 |
| D. | 58 |
| Answer» C. 44 | |