Lakshya Education MCQs

Question: Natural silica
A.Mainly contains quartz
B.Is not stable at high temperature
C.Transforms to other allotropic forms i.e tridymite and cristoballite involving very high volume changes
D.All of the above
Answer: Option D

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More Questions on This Topic :

Question 1. Carborundum used for making crucibles for melting non-ferrous metals is chemically
  1.    Silicon carbide
  2.    Silicon nitride
  3.    Crystalline magnesia
  4.    Zirconium sulphate
Answer: Option A
Question 2. Dilatometer is used for the determination of __________ of refractories.
  1.    Modulus of rupture
  2.    Permanent linear change
  3.    Resistance to CO attack
  4.    RUL
Answer: Option B
Question 3. Which one contains minimum percentage of SiO₂?
  1.    Firebrick
  2.    Sillimanite
  3.    Semi-silica
  4.    Aluminous firebrick
Answer: Option B
Question 4. Magnesite refractories are used for the construction of those furnaces, which are
  1.    Not required to resist the corrosive action of basic slag
  2.    Not subjected to fluctuation in temperature
  3.    Used for raising & maintaining high temperature
  4.    Both (b) and ©
Answer: Option D
Question 5. __________ nozzles are used in continuous casting of steel,
  1.    Zircon
  2.    Thoria
  3.    Carborundum
  4.    Beryllia
Answer: Option A
Question 6. Which is not an alumino-silicate refractory?
  1.    Fireclay bricks
  2.    Mullite bricks
  3.    Tar dolomite bricks
  4.    High alumina bricks
Answer: Option C

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