Q1: Out of the following, the __________ pipe has the least corrosion resistance.

ANS:D - wrought iron

Out of the options provided, cast iron pipe has the least corrosion resistance. While all materials can corrode to some extent, cast iron is particularly susceptible to corrosion, especially in environments with high moisture or acidity. Cast iron pipes are prone to rusting, which can lead to degradation and eventual failure of the pipe. Additionally, cast iron is susceptible to dezincification, a form of corrosion that occurs when zinc is selectively removed from the iron matrix, leaving behind a porous and weakened structure. In contrast, materials like copper, mild steel, and wrought iron typically have better corrosion resistance compared to cast iron. Copper forms a protective oxide layer that helps prevent further corrosion, mild steel can be protected through coatings or alloying, and wrought iron has inherent corrosion resistance due to its low carbon content and slag inclusions. Therefore, among the options provided, cast iron pipe has the least corrosion resistance.