The crystal layers in graphite are held together by

Step 1: Analyze the question We're asked what holds the layers of graphite to one another. Note that this is different from what holds the atoms within a layer.

Step 2: The concept Graphite is an allotrope of carbon with a layered structure:

• Within each layer: Each carbon atom is covalently bonded to three other carbon atoms, forming flat hexagonal rings. The fourth electron is delocalised, which is why graphite conducts electricity.
• Between layers: The layers are held together only by weak van der Waals forces (weak intermolecular attractions).

Step 3: Apply it to the options

• A. Covalent bond: this holds atoms together within a layer, not the layers to each other. ✗
• B. Electrostatic forces: this is too general and normally describes ionic attraction. It is not the standard answer for graphite. ✗
• C. Ionic bond: graphite contains only carbon, so no ions are present. ✗
• D. Van der Waal's forces: this correctly describes the weak attraction between layers. ✓

Step 4: Why this matters Because the forces between layers are weak, the layers slide over one another easily. This explains why graphite is soft and slippery, and why it is used as a lubricant and in pencil "lead".

Answer: D. van der Waal's forces

Exam tip: Remember "covalent in the layer, van der Waals between the layers." Compare diamond, where every carbon is covalently bonded in a rigid 3D network, making it very hard. Graphite's weak interlayer forces make it soft.