Free Chemical Process Principles MCQs with Answers

• A. Metallurgical
• B. Cement
• C. Fertiliser
• D. Power

Explanation: The metallurgical industry consumes the most refractories because furnaces, converters, ladles, and other steelmaking equipment operate at…

• A. Silica bricks
• B. High alumina bricks
• C. Low duty firebricks
• D. Graphite blocks

Explanation: High-alumina bricks withstand the severe temperatures, chemical attack, and vacuum conditions of steel degassing better than ordinary…

• A. Neutral refractory
• B. Acidic refractory
• C. Basic refractory
• D. Fired at a temperature of 600°C only

Explanation: Chromite refractories are classified as neutral because chromium oxide can resist both acidic and basic slags better than strongly acidic…

• A. Has high fusion temperature (> 3000°C) but poor resistance to thermal shock
• B. All A., B. and C.
• C. Which is expensive & radioactive, is used in crucibles for melting high purity metals
• D. Has high resistance to basic slags

Explanation: Thoria has an extremely high melting point, good resistance to basic slags, and is used for high-purity metal crucibles despite its cost…

• A. Firing temperature
• B. Composition
• C. Shape
• D. Texture

Explanation: Cold crushing strength is governed mainly by composition, firing temperature, and texture or porosity.

• A. None of these
• B. Tridymite
• C. Quartz
• D. Cristobalite

Explanation: Silica undergoes the tridymite-to-cristobalite transformation at about 1470°C, so cristobalite is the stable polymorph from 1470°C up to…

• A. 1150
• B. 1300
• C. 1450
• D. 1550

Explanation: Fireclay bricks generally have a safe service limit of roughly 1500 to 1550°C, depending on grade and operating conditions.

• A. High crushing strength
• B. High thermal conductivity
• C. Non-wetting characteristic
• D. None of these

Explanation: Carbon is poorly wetted by molten iron and slag, so the solidified material does not readily adhere to the carbon hearth and form a skull.

• A. Carbides
• B. Nitrides
• C. Borides
• D. Oxides

Explanation: Super refractories are generally produced from very pure, high-melting oxides such as alumina, magnesia, zirconia, and thoria.

• A. Have very low (50 kg/cm2) cold crushing strength (C.C.S.), and cannot be used in metalcase
• B. Have very low thermal co-efficient of expansion
• C. Are not at all resistant to the corrosive action of iron oxide
• D. Have better spalling resistance than chrome magnesite refractories
• E. form

Explanation: Magnesite-chrome refractories, with magnesia as the major constituent, generally offer better resistance to spalling than chrome-magnesite…

• A. Strength
• B. Both A. & B.
• C. Abrasion resistance
• D. Neither A. nor B.

Explanation: Excess lime in silica-brick bonding increases the glassy bonding phase and weakens the brick, reducing both mechanical strength and…

• A. Do not burn/oxidise, when exposed to air on heating
• B. Do not resist temperature fluctuations
• C. Are not attacked by slags, as they are not wetted by melts
• D. Have extremely low thermal & electrical conductivities

Explanation: Carbon refractories are poorly wetted by most molten slags, so slag penetration and attack are limited.

• A. Basic
• B. Neutral
• C. High alumina
• D. Insulating

Explanation: Sillimanite, Al₂SiO₅, contains a high proportion of alumina and is therefore classified as a high-alumina refractory.

• A. High thermal conductivity
• B. Low porosity
• C. Both A. and B.
• D. Neither A. nor B.

Explanation: An insulating refractory should have low thermal conductivity and generally high porosity to reduce heat flow.

• A. Silica
• B. Periclase
• C. Lime
• D. None of these

Explanation: Ganister is a hard, finely divided form of quartz or nearly pure silica used to make silica refractories.

• A. Used for furnace insulation
• B. At the hearth bottom of the furnace on which stock is placed
• C. Used in the roof of the furnace
• D. None of these

Explanation: RUL measures how well a refractory supports a mechanical load at high temperature without deforming.

• A. Firebricks
• B. Sillimanite
• C. Silicon carbide bricks
• D. Silica bricks

Explanation: Silica bricks undergo significant volume changes and have poor resistance to thermal shock during repeated heating and cooling.

• A. L.D. converter
• B. Blast furnace
• C. Soaking pit
• D. Coke ovens

Explanation: The L.D. converter consumes large quantities of refractory because its lining is exposed to severe thermal, chemical and mechanical attack…

• A. Are stored under controlled temperature & humidity to avoid hydration
• B. All A., B. and C.
• C. Have poorer hydration resistance than pitch bonded bricks
• D. Are used in outer lining of L.D. converters

Explanation: Tar-bonded dolomite bricks must be protected from moisture because dolomite can hydrate, and they are commonly used in the outer lining of…

• A. None of these
• B. Increased thermal conductivity of brick
• C. Oxidising condition in the furnace
• D. Decreased viscosity of slag

Explanation: Heating lowers the viscosity of molten slag, allowing it to flow, penetrate pores and react with the refractory more readily.