Capacity of a refractory brick to withstand-sudden changes in temperature is denoted by the property called_________________?

Related Mcqs:

1. An insulating refractory brick should have high porosity and low thermal conductivity. Which of the following is not used for inducing porosity in the insulating refractory bricks during its manufacture ?

   A. Cork
   B. Saw dust
   C. Sand
   D. Chemically prepared foam

2. Addition of zircon to silica refractory brick improves its_________________?

   A. Crushing strength
   B. Resistance to slag attack
   C. Both A. and B.
   D. Neither A. nor B.

3. Thermal diffusivity of a refractory brick is high, when its ______________ is high?

   A. Density
   B. Specific heat
   C. Thermal conductivity
   D. None of these

4. Spalling of silica bricks occurs due to abrupt volume changes, when it is cooled below a temperature of ______________ °C?

   A. 770
   B. 570
   C. 270
   D. 70

5. With rise in temperature, the heat capacity of a substance___________________?

   A. Increases
   B. Decreases
   C. Remains unchanged
   D. Either A. or B.; depends on the substance

6. A perfectly insulated container of volume V is divided into two equal halves by a partition. One side is under vacuum, while the other side has one mole of an ideal gas (with constant heat capacity) at 298 K. If the partition is broken, the final temperature of the gas in the container___________________?

   A. Will be greater than 298 K
   B. Will be 298 K
   C. Will be less than 298 K
   D. Cannot be determined

7. Which is an acidic refractory ?

   A. Magnesite
   B. Dolomite
   C. Fireclay
   D. Chrome magnesite

8. Water content in ground refractory material to be shaped into bricks by hand moulding is about _____________ percent?

   A. 5
   B. 20
   C. 40
   D. 55

9. Test piece for determination of RUL of a refractory is heated in a/an__________________?

   A. Oxidising atmosphere
   B. Reducing atmosphere
   C. Electric furnace
   D. Neutral atmosphere

10. Fusion point of a basic refractory material is________________?

    A. Reduced by the addition of acid oxides
    B. Increased by the addition of acid oxides
    C. Not affected by the addition of acid oxides
    D. Always less than 1000°C