Lakshya Education MCQs

Question: Sillimanite is a __________ refractory.
C.High alumina
Answer: Option C

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More Questions on This Topic :

Question 1. Addition of grog in fireclay brick during its manufacture is advantageous, because it results in
  1.    Less shrinkage in heating, decreased apparent porosity & increased specific gravity
  2.    High strength & thermal spalling resistance
  3.    Less addition of water to get a workable plasticity & lesser time required for drying the raw refractories and hence increased rate of production
  4.    All of the above
Answer: Option D
Question 2. Which form of silica has the highest specific gravity?
  1.    Quartz
  2.    Cristobalite
  3.    Tridymite
  4.    All of the above
Answer: Option A
Question 3. What is Thoria?
  1.    Thoria Has high fusion temperature (> 3000°C) but poor resistance to thermal shock
  2.    Thoria Has high resistance to basic slags
  3.    Which is expensive & radioactive, is used in crucibles for melting high purity metals
  4.    All of the above
Answer: Option D
Question 4. Tar bonded dolomite bricks
  1.    Are stored under controlled temperature & humidity to avoid hydration
  2.    Are used in outer lining of L.D. converters
  3.    Have poorer hydration resistance than pitch bonded bricks
  4.    All of the above
Answer: Option D
Question 5. With increasing alumina content, the fusion point of high alumina refractories
  1.    Increases
  2.    Decreases
  3.    Remains constant
  4.    May increase or decrease ; depends on its alumina content
Answer: Option A
Question 6. Silica bricks have low spalling resistance below 600°C, due to its
  1.    Very high thermal conductivity
  2.    High co-efficient of expansion upto this temperature
  3.    High thermal diffusivity
  4.    Low refractoriness
Answer: Option B

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