Permeability of bricks is a measure of the_________________?

A. Refractoriness
B. Melting point
C. Rate at which a fluid will pass through the pores
D. Expansion during heating

Carborundum used for making crucibles for melting non-ferrous metals is chemically________________?

A. Silicon carbide
B. Silicon nitride
C. Crystalline magnesia
D. Zirconium sulphate