For bricks used in the combustion chamber and dome of blast-furnace stoves, which combination of properties is most important?

Introduction / Context:
Blast-furnace stoves alternate between heating and blasting cycles. Bricks in the combustion chamber and dome face extreme temperatures, thermal shocks, and mechanical loads, requiring a balanced property set for durability.

Given Data / Assumptions:

• High refractoriness ensures shape retention at peak operating temperatures.
• Thermal-shock resistance is vital due to cycling.
• Adequate strength/density confers structural robustness and wear resistance.

Concept / Approach:
No single property suffices. The material must withstand heat (refractoriness), resist crack generation under rapid temperature swings (spalling resistance), and bear mechanical stresses (strength/density). Therefore, a combination of all three properties is essential for long service life.

Step-by-Step Solution:
List the dominant degradation modes: high T, cycling, mechanical loads.Map each mode to a key material property.Conclude that all three properties must be high.

Verification / Alternative check:
Stove lining specifications emphasize refractoriness, shock resistance, and structural strength simultaneously for these zones.

Why Other Options Are Wrong:
Focusing on only one property invites premature failure via the other mechanisms.

Common Pitfalls:
Overemphasizing refractoriness and overlooking thermal-shock demands inherent to cycling operation.

Final Answer:
All (a), (b) and (c)