All Free Chemical Engineering MCQs with Answers

• A. Fireclay
• B. Silica
• C. Chrome magnesite
• D. None of these

Explanation: Chrome magnesite is a basic refractory because its principal constituents, magnesia and chromite, resist attack by basic slags.

• A. Attack by basic slag
• B. Abrasion
• C. Disintegration on sudden change of temperature
• D. Both B. and C.

Explanation: Magnesite refractories resist basic slag well, but they have poor resistance to abrasion and thermal shock, causing disintegration during…

• A. High co-efficient of expansion upto this temperature
• B. Very high thermal conductivity
• C. High thermal diffusivity
• D. Low refractoriness

Explanation: Silica undergoes marked thermal expansion and structural changes below about 600°C, producing internal stresses and poor spalling…

• A. CaO
• B. MgO
• C. Al2O3
• D. SiO2

Explanation: Periclase is essentially crystalline magnesium oxide, MgO, obtained from magnesite or other magnesium-bearing materials.

• A. Very high temperatures are involved
• B. Highly reducing conditions are involved
• C. All A., B. and C.
• D. Presence of iron or silica is harmful

Explanation: High-purity alumina fused-mullite linings are selected for very high temperatures, reducing atmospheres, and service where iron or silica…

• A. Castables
• B. Cements
• C. Mortars
• D. None of these

Explanation: Castables are dry mixtures of refractory aggregates and hydraulic or other bonding materials that are mixed with water and cast into…

• A. Composite material containing both ceramic & metallic constituents
• B. All A., B. and C.
• C. Used in space vehicles, missiles & nuclear energy plants
• D. Having high strength & resistance to high temperature

Explanation: Cermets combine ceramic particles or phases with a metallic constituent, giving high-temperature strength and wear resistance.

• A. Greater diffusivity
• B. Low specific heat
• C. All A., B. and C.
• D. Low thermal co-efficient of expansion

Explanation: Spalling is reduced when temperature gradients and thermal stresses are small, which is promoted by high thermal diffusivity, low specific…

• A. Corundum
• B. Periclase
• C. Bauxite
• D. Carborundum

Explanation: Carborundum is the industrial name for silicon carbide, the principal raw material used in silicon carbide refractories.

• A. Both A. and B.
• B. Continuous casting systems
• C. Slide gate in teeming laddies
• D. Neither A. nor B.

Explanation: Alumina-graphite bricks resist erosion, thermal shock and molten-metal attack, so they are used in slide gates and continuous-casting…

• A. 5 to 10
• B. 20 to 30
• C. 45 to 60
• D. 60 to 75

Explanation: Silica bricks commonly have about 20 to 30% apparent porosity, which provides a balance between thermal resistance and mechanical…

• A. Coke oven walls
• B. Dome and upper portion of B.F. stoves
• C. Beehive coke ovens
• D. Open hearth furnace roof

Explanation: Silica refractories are used in coke-oven walls, blast-furnace stove domes and open-hearth roofs because they tolerate high temperatures…

• A. Both B. and C.
• B. Voids
• C. Shrinkage
• D. Green strength

Explanation: Rapid drying can produce nonuniform moisture removal, causing greater shrinkage and internal voids or cracks in the moulded refractory.

• A. Superduty fireclay
• B. Silica
• C. Chromite
• D. None of these

Explanation: Silica bricks are traditionally used in basic electric-furnace roofs because they withstand the high operating temperature and have good…

• A. Silica
• B. Fireclay
• C. Chrome magnesite
• D. Zirconia

Explanation: The outer combustion chamber of a blast-furnace stove is commonly lined with fireclay bricks, which provide adequate refractoriness at…

• A. Not required to resist the corrosive action of basic slag
• B. Not subjected to fluctuation in temperature
• C. Both B. and C.
• D. Used for raising & maintaining high temperature

Explanation: Magnesite refractories withstand high temperatures and basic environments but have poor resistance to sudden temperature changes.

• A. Oxidising atmosphere
• B. Reducing atmosphere
• C. Neutral atmosphere
• D. Electric furnace

Explanation: Refractoriness under load is determined by heating a loaded test piece at a controlled rate in an electric furnace until specified…

• A. All A., B. and C.
• B. Converted to Tridymite on firing between 870 to 1470°C
• C. Transformed to Cristobalite on heating above 1470°C
• D. Stable form of silica upto 870°C

Explanation: Silica changes progressively from quartz to tridymite between about 870 and 1470°C, and to cristobalite above about 1470°C.

• A. Electrical conductivity
• B. Cost
• C. Thermal conductivity
• D. Fusion point

Explanation: Beryllia has better high-temperature performance than alumina, including higher thermal conductivity and a higher fusion point, but it is…

• A. Remain same
• B. Decreases
• C. Increases
• D. May increase or decrease

Explanation: Greater porosity generally improves thermal-spalling resistance because it lowers thermal conductivity and provides void space to relieve…