Difficulty: Easy
Correct Answer: PVC
Explanation:
Introduction / Context:Plumbing products must resist water, household chemicals, and impact, while being economical and easy to fabricate. Modern cisterns and fittings often favor thermoplastics that can be injection-molded or blow-molded with integrated features and robust sealing surfaces.
Given Data / Assumptions:
Concept / Approach:PVC (particularly unplasticized PVC, uPVC) offers good chemical resistance, rigidity, and weldability/glue-ability for plumbing applications. It is widely used in pipes, fittings, and cistern housings. Other listed polymers either lack the necessary toughness/stiffness balance, are more expensive, or are used for different applications (e.g., perspex for glazing, EPS for insulation/packaging).
Step-by-Step Solution:
Match requirements to materials: water resistance + easy fabrication → PVC.Reject EPS: too brittle/foamed; structural integrity insufficient for tanks under hydrostatic load.Reject perspex: transparent acrylic is more brittle and more expensive for this use.Reject saturated polyester: typically thermoset composites; less common for commodity cistern bodies.Verification / Alternative check:Commercial plumbing catalogs and building-product specifications show uPVC cisterns and uPVC fittings as standard offerings.
Why Other Options Are Wrong:
Common Pitfalls:Confusing ceramic/porcelain cisterns with polymer ones; the question specifically targets plastic cisterns.
Final Answer:PVC
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