Which one of the following materials is very hard and very ductile?
- ACarborundum
- BTungsten
- CCast iron
- DNichromeCorrect
Explanation
Nichrome is the correct answer because it uniquely satisfies both criteria mentioned in the question. It is an alloy of nickel and chromium known for being very hard, which allows it to withstand high temperatures and mechanical stress without deforming. Simultaneously, it is very ductile, meaning it can be easily drawn into thin wires, which is essential for its primary use as heating elements in appliances like toasters and heaters.
In contrast, Carborundum is extremely hard but very brittle, not ductile. Tungsten is very hard and has the highest melting point but is generally difficult to work with and less ductile than Nichrome at room temperature. Cast iron is hard but notoriously brittle and cannot be drawn into wires. Therefore, Nichrome is the most suitable choice.
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