Porcelain, a vitrified ceramic, finds widespread use because of its strength, chemical resistance, and electrical insulating properties. Identify the applications in which porcelain is commonly used in engineering and domestic practice.

Introduction / Context:
Porcelain is a dense, vitrified ceramic made from kaolin, feldspar, and quartz, fired at high temperatures. Its microstructure yields low porosity, high dielectric strength, and good chemical durability, enabling both structural and functional uses. The question probes recognition of this application breadth.

Given Data / Assumptions:

• Porcelain is glassy–crystalline with very low water absorption.
• It resists many acids and alkalis and is an excellent electrical insulator.
• Mechanical strength and surface hardness suit sanitary and laboratory ware.

Concept / Approach:

These properties naturally align with sanitary fixtures, electrical insulators (pin, disc, post types), chemical storage and laboratory vessels, and reactor or process vessels for corrosive media at moderate temperatures. The vitrified body and glaze make porcelain hygienic and easy to clean, while its dielectric properties make it indispensable in power systems.

Step-by-Step Solution:

Verification / Alternative check:

Product catalogs and codes for sanitary ware and insulators extensively specify porcelain grades and tests (water absorption, dielectric breakdown).

Why Other Options Are Wrong:

Choosing any single application ignores the full, established range of porcelain uses.

Common Pitfalls:

Confusing earthenware or stoneware with porcelain; underestimating porcelain's dielectric strength in HV insulators.

Final Answer:

All of the above