Pick out the wrong statement.
A. Refractories used in muffle furnace should have low thermal conductivity
B. The electrical resistivity of refractories drops rapidly with rise in temperature
C. For reducing spalling tendency, the refractory should be well fired and its porosity should be more
D. Refractoriness under load (RUL) of a refractory is always less than its refractoriness
Answer: Option A
Fusion point of an acidic refractory material is
A. Increased by the addition of basic oxides
B. Reduced by the addition of basic oxides
C. Not affected by the addition of basic oxides
D. Not affected by the addition of basic oxides
Which of the following is not a high alumina refractory material?
A. Kyanite
B. Sillimanite
C. Diaspore
D. Periclase
Magnesite refractories are generally not used in the
A. Electric furnace walls
B. Steel melting furnace
C. Open hearth furnace
D. Burning zone of cement kilns
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