Step 1: Understanding the Concept:
Graphite is an allotrope of carbon with a unique layered structure.
Within each layer, carbon atoms are arranged in hexagonal rings. The atoms in a layer are held together by strong covalent bonds formed by \(sp^2\) hybridization.
Between these layers, there are only weak van der Waals forces.
Because the intra-layer bonding is strong and covalent, the distance between atoms is short. Conversely, because the inter-layer forces are weak, the gap between layers is relatively large.
Step 2: Detailed Explanation:
1. **Intra-layer bond length (X):** Within the planar hexagonal network, each carbon atom is bonded to three others. Due to partial double bond character (delocalized pi electrons), the bond length (141.5 pm) is shorter than the standard single C-C bond found in diamond (154 pm).
2. **Inter-layer distance (Y):** Because the layers are not chemically bonded to each other, they are spaced far apart. This distance is 340 pm. This large distance and weak inter-layer forces allow the layers to slide past each other, making graphite slippery and a good lubricant.
Step 3: Final Answer:
The values for X and Y are 141.5 pm and 340 pm respectively.
This matches option (B).