Free Chemical Process Principles MCQs with Answers

• A. Gas retorts
• B. Glass melting furnace
• C. Crucibles
• D. Pottery furnace

Explanation: Sillimanite refractories are used in applications such as pottery and glass furnaces and in crucibles, but gas retorts generally use other…

• A. High spalling resistance
• B. High resistance to fusion
• C. Low spalling resistance
• D. Low porosity

Explanation: Refractoriness is the ability of a refractory material to withstand very high temperatures without softening or fusing.

• A. Increasing its porosity
• B. Using a coarser grog during its manufacture
• C. Making it denser
• D. Decreasing its thermal co-efficient of expansion

Explanation: Spalling resistance improves with some porosity, coarser grog, and a lower thermal expansion coefficient because these reduce thermal…

• A. All A., B. and C.
• B. High resistance to spalling
• C. High strength and density
• D. High refractoriness

Explanation: The combustion chamber and dome of a blast-furnace stove operate at very high temperatures, so high refractoriness is the key requirement.

• A. Composition
• B. All A., B. and C.
• C. Firing temperature
• D. Texture

Explanation: Cold crushing strength is affected by the refractory's composition, texture or structure, and firing temperature, since all influence…

• A. 8
• B. 24
• C. 44
• D. 58

Explanation: Magnesite bricks are relatively dense refractories, and their maximum apparent porosity is commonly taken as about 24%.

• A. Bottom of soaking pits
• B. Between acid & basic linings in basic open hearth furnaces to prevent their chemical action
• C. with each other
• D. Both A. & B.
• E. Neither A. and B.

Explanation: Chromite refractories are used at the bottom of soaking pits and as an intermediate lining between acidic and basic refractories.

• A. Are wetted by molten iron
• B. Are used in the hearth of blast furnace
• C. Are acidic in nature
• D. All A., B. and C.

Explanation: Carbon blocks are not readily wetted by molten iron and are therefore suitable for the hearth of a blast furnace.

• A. All A., B. and C.
• B. Flues
• C. Chimney linings
• D. Furnaces allowed to cool frequently

Explanation: Fireclay bricks tolerate ordinary furnace conditions and are widely used in furnaces, flues, and chimney linings.

• A. Thermal conductivity
• B. Spalling resistance
• C. Fusion point
• D. Slag penetration resistance

Explanation: High-density refractories have less pore space to absorb thermal expansion and therefore develop greater thermal stresses during rapid…

• A. Neither A. nor B.
• B. Corrosion by layer of slag
• C. Both A. & B.
• D. Washing action of metal

Explanation: Mullite bricks in the upper portion of a hot-metal mixer are selected mainly to resist the erosive washing action of moving hot metal.

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

Explanation: Alumina has a very high melting point, so increasing its proportion raises the temperature at which the refractory softens or melts.

• A. Poor resistance to the penetration of molten slag, metal & flue gases
• B. All A., B. and C.
• C. Better thermal spalling resistance
• D. Poor heat conductivity & low strength

Explanation: High porosity makes bricks more insulating and resistant to thermal shock, but it also lowers strength and permits easier penetration by…

• A. Increases
• B. Does not affect
• C. Lowers
• D. Either A. or B.; depends on its quantity

Explanation: MgO acts as a basic flux in alumino-silicate refractories and can form lower-melting compounds with silica and alumina.

• A. ThO2
• B. Al2O3
• C. ZrSO4
• D. 3Al2O3.2SiO2

Explanation: Mullite is the alumino-silicate compound 3Al₂O₃·2SiO₂. Its high-temperature stability makes it valuable in refractory applications.

• A. Fusion point
• B. Spalling resistance
• C. Slag penetration resistance
• D. Refractoriness under load (RUL)

Explanation: The panel test repeatedly heats and cools refractory test pieces and observes cracking or failure caused by thermal shock.

• A. 30
• B. 50
• C. 70
• D. 90

Explanation: High-alumina refractories are classified by increasing Al₂O₃ content and may contain roughly 50 to 90% alumina.

• A. 5
• B. 20
• C. 40
• D. 55

Explanation: Hand moulding requires enough water to provide plasticity, typically about 20% of the ground refractory mix.

• A. Silicon carbide
• B. Magnesite
• C. Dolomite
• D. Chrome magnesite

Explanation: Magnesite, dolomite, and chrome-magnesite are basic refractories because their oxides react preferentially with acidic impurities.

• A. Firebrick
• B. Sillimanite
• C. Magnesite
• D. Aluminous firebrick

Explanation: Sillimanite contains about Al2O3, more than ordinary firebrick and magnesite; aluminous firebrick commonly has a lower alumina content…