Thoria__________________?

Related Mcqs:

1. Bauxite calcining rotary kilns are lined with ________________ bricks?

   A. Fireclay
   B. Carbon
   C. 85% alumina
   D. Corundum

2. An ideal refractory should have high__________________?

   A. Spalling rate
   B. Fusion point
   C. Shrinkage ability
   D. None of these

3. Which one contains maximum percentage of Al2O3 ?

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

4. Which of the following impurities reduces the refractoriness of magnesite bricks ?

   A. Al2O3
   B. CaO
   C. SiO2
   D. All A., B. & C.

5. Insulating refractories should have_______________?

   A. High porosity
   B. Low thermal conductivity
   C. Both A. and B.
   D. Neither A. not B.

6. Quartz is___________________?

   A. Stable form of silica upto 870°C
   B. Converted to Tridymite on firing between 870 to 1470°C
   C. Transformed to Cristobalite on heating above 1470°C
   D. All A., B. and C.

7. Magnesite refractories are used for the construction of those furnaces, which are________________?

   A. Not required to resist the corrosive action of basic slag
   B. Not subjected to fluctuation in temperature
   C. Used for raising & maintaining high temperature
   D. Both B. and C.

8. High refractoriness of refractory bricks means, that it has a________________?

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

9. Addition of grog in fireclay brick during its manufacture is advantageous, because it results in_____________________?

   A. Less shrinkage in heating, decreased apparent porosity & increased specific gravity
   B. High strength & thermal spalling resistance
   C. Less addition of water to get a workable plasticity & lesser time required for drying the raw
   refractories and hence increased rate of production
   D. All A., B. and C.

10. Which is not a natural insulating material ?

    A. Diatomaceous earth/kieselgur
    B. Asbestos
    C. Vermiculite
    D. None of these