Cast iron is hard but pure iron is soft in nature. Explain why ?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Composition:**
- Cast iron contains a significant amount of carbon, typically ranging from 2.5% to 5%. This carbon content is crucial in determining the properties of the metal.
- In contrast, pure iron has a carbon content of 0%, meaning it does not have the same alloying elements that contribute to hardness.

2. **Effect of Carbon on Hardness:**
- The presence of carbon in cast iron leads to the formation of various carbon compounds, such as cementite (Fe₃C), which contribute to the hardness and brittleness of the material.
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