1. Porosity is induced in insulating refractories by adding
2. A steel member used in the furnace construction to take the thrust of the brickwork is called
3. Pick out the wrong statement.
4. 10 to 30% magnesite is added to chromite to produce chrome-magnesite refractories. Magnesite addition is mainly done to improve the __________ of chromite.
5. Which is a basic refractory?