Graphite is a soft solid lubricant extremely difficult to melt. The reason for this anamolous behaviour of graphite -

Options

A. Carbon atoms are arranged in large plates of rings of strongly bound carbon atoms with weak interplate bonds
B. Is a non-crystalline substance
C. Has molecules of variable molecular masses like polymers
D. Is an allotropic form of diamond.

Answer

**Step-by-Step Solution:**

1. **Understanding Graphite's Structure:**
- Graphite has a unique structure known as a "layered" or "2D" structure. In this structure, carbon atoms are arranged in sheets or layers that are stacked on top of each other.

2. **Bonding in Graphite:**
- Within each layer, each carbon atom is covalently bonded to three other carbon atoms, forming a strong network of bonds. This bonding gives the layers their stability and strength.

3. **Weak Inter-layer Forces:**
- The layers themselves are held together by weak van der Waals forces (also referred to as weak inter-plate bonds). These forces are much weaker than the covalent bonds within the layers.

4. **Lubricating Properties:**
- Because the layers are only weakly bonded to each other, they can slide over one another easily. This property allows graphite to act as a lubricant, making it soft and slippery.

5. **Melting Point:**
- The strong covalent bonds within the layers require a significant amount of energy to break. As a result, melting graphite is extremely difficult because it would require overcoming these strong bonds. The weak inter-layer forces do not contribute significantly to melting, as they are not strong enough to hold the structure together under high temperatures.

6. **Conclusion:**
- The anomalous behavior of graphite, being a soft solid lubricant that is difficult to melt, is primarily due to its layered structure, strong covalent bonds within the layers, and weak inter-layer forces that allow the layers to slide past each other.

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