Ceramic fundamentals: pick the WRONG statement about ceramics, glass formation, brittleness, vitrification, and conductivity of non-oxide ceramics.

Introduction / Context:
General ceramic science covers glass formation, sintering, vitrification, mechanical behaviour, and electrical properties. This question asks you to identify the incorrect statement among common truths about ceramics and glasses.

Given Data / Assumptions:

• “Glass” refers to an amorphous, non-crystalline solid formed from a melt upon cooling, often workable in a viscous state at elevated temperature.
• “Vitrification” describes the development of glassy phase during firing of many ceramic bodies.
• Non-oxide ceramics (carbides, nitrides, borides) often show semiconducting or conductive behaviour.

Concept / Approach:
During firing, many clay-based and alumino-silicate ceramics undergo partial vitrification: a glassy phase forms that helps densify and bond grains, increasing strength. Therefore, claiming that ceramics “do not undergo vitrification” is false. Glasses indeed become viscous fluids upon heating and can be shaped by blowing, pressing, or drawing. Ceramics are typically brittle due to ionic/covalent bonding and limited dislocation mobility. Non-oxide ceramics (e.g., SiC, TiC, TiN, BN variants) can be semiconducting or even fairly conductive depending on composition and defect chemistry.

Step-by-Step Solution:
Evaluate (a): accurate description of glass behaviour.Evaluate (b): false; many ceramics do vitrify to some extent on firing.Evaluate (c): true; brittle fracture is common.Evaluate (d): true; many non-oxides show semiconducting features.

Verification / Alternative check:
Phase diagrams and firing curves for stoneware, porcelain, and fireclay bodies show glass-phase formation; electrical characterisation of SiC and Si3N4 confirms semiconducting trends.

Why Other Options Are Wrong:
(a), (c), and (d) are broadly correct statements in materials science.

Common Pitfalls:
Confusing “all ceramics” with “glasses”; not all ceramics vitrify to the same extent, but many do.

Final Answer:
Ceramic materials do not undergo vitrification on heating.