Metal pipe materials – properties and usage: Which set of statements about copper and wrought-iron (galvanised) pipes is correct in water-supply practice?

Introduction / Context:
Choosing appropriate pipe material requires balancing mechanical strength, corrosion resistance, weight, and durability. Copper and wrought-iron (galvanised) pipes have long histories in building plumbing and distribution networks.

Given Data / Assumptions:

• Statements address relative properties compared to cast iron and common nomenclature.
• General potable-water environments (not highly aggressive industrial fluids).

Concept / Approach:
Copper exhibits good general corrosion resistance in typical potable water ranges and is widely used in building plumbing. Wrought iron is lighter than cast iron but, if unprotected, corrodes faster and is less durable; galvanising (zinc coating) produces galvanised iron (G.I.) pipes with improved corrosion resistance.

Step-by-Step Solution:
Compare densities and wall thickness: wrought iron pipes are lighter than cast iron.Assess corrosion: unprotected wrought iron corrodes relatively quickly.Define G.I.: zinc-coated wrought-iron/steel pipes are termed galvanised iron pipes.Copper’s general resistance in potable service is good (within typical pH ranges).

Verification / Alternative check:
Building codes and material standards document widespread use of copper and G.I. with the above general properties and limitations (e.g., copper not recommended for highly acidic/alkaline waters without controls).

Why Other Options Are Wrong:
Each separate statement is correct in general potable contexts; the most complete answer is “All the above.”

Common Pitfalls:

• Interpreting “highly resistant” as universally inert; extreme pH or specific ions can still attack copper.

Final Answer:
All the above