Questions and answers for exam Preparation

MCQs

Total Questions : 868 | Page 87 of 87 pages

Question 861. Permeability of bricks is a measure of the_________________?

Refractoriness
Melting point
Rate at which a fluid will pass through the pores
Expansion during heating

Discuss Question

Answer: Option C. -> Rate at which a fluid will pass through the pores
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 862. Carborundum used for making crucibles for melting non-ferrous metals is chemically________________?

Silicon carbide
Silicon nitride
Crystalline magnesia
Zirconium sulphate

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Answer: Option A. -> Silicon carbide
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 863. Pick out the wrong statement ?

Electrical conductivity of refractory is not important, when these are to be used in electrical furnaces
Graphite and metals are the good electrical conductor among the refractories and others are all electrical insulators
Refractories used for lining electrical furnaces should ordinarily have very low electrical conductivity
Electrical conductivity of porous refractory material is low

Discuss Question

Answer: Option A. -> Electrical conductivity of refractory is not important, when these are to be used in electrical furnaces
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 864. Pick out the wrong statement?

Sand & coke is the main raw material for the manufacture of silicon carbide
Carbon refractories cannot be used in the furnaces operating under reducing conditions
Mullite can be obtained by the heating of alusite, kyanite or sillimanite
Silica occurs in nature in all cellular, amorphous or crystalline form

Discuss Question

Answer: Option B. -> Carbon refractories cannot be used in the furnaces operating under reducing conditions
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 865. Pick out the wrong statement?

Insulating refractories used in place of regular refractory bricks are usually called light weight refractories, and they have similar composition as
Graphite refractories are also called plumbago refractories
Superduty fireclay bricks correspond to a pyrometric cone equivalent of 26-28
Calcined magnesite is also called dead burnt magnesite

Discuss Question

Answer: Option C. -> Superduty fireclay bricks correspond to a pyrometric cone equivalent of 26-28
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 866. Pick out the wrong statement ?

Refractories used in muffle furnace should have low thermal conductivity
The electrical resistivity of refractories drops rapidly with rise in temperature
For reducing spalling tendency, the refractory should be well fired and its porosity should be more
Refractoriness under load (RUL) of a refractory is always less than its refractoriness

Discuss Question

Answer: Option A. -> Refractories used in muffle furnace should have low thermal conductivity
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 867. Pick out the wrong statement?

Fluxing material like lime is added in clay to reduce the vitrification temperature
Main constituents of clay are alumina and silica
Addition of sand in ceramic materials makes it non-plastic, increases its fusion point and reduces its shrinkage on burning
Vitrification of fireclay material is done to increase its porosity

Discuss Question

Answer: Option D. -> Vitrification of fireclay material is done to increase its porosity
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!

Question 868. Pick out the wrong statement ?

A ceramic material which becomes fluid upon heating and can be moulded in liquid/viscous state is termed s glass
Ceramic materials do not undergo vitrification on heating
Ceramic materials are brittle in nature
Non-oxide ceramic materials generally act as a semi-conductor

Discuss Question

Answer: Option B. -> Ceramic materials do not undergo vitrification on heating
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!