Identify the shapes of H3O+ and CO2. Explain why graphite is a lubricant and identify two allotropes of carbon based on their descriptions.

10. ii) The shape of $\text{H}_3\text{O}^+$ is trigonal pyramidal.

iii)
The shape of $\text{CO}_2$ is linear.

12. Graphite is used as a lubricant because of its unique structure and bonding. It consists of layers of carbon atoms arranged in hexagonal rings, where each carbon atom is covalently bonded to three others within the same layer. These layers are held together by weak intermolecular forces (van der Waals forces). The weak forces allow the layers to slide easily over each other, making graphite soft and slippery, which is ideal for lubrication.

13. The diagram shows two allotropes of carbon:

• Allotrope M is graphite.
• Allotrope N is amorphous carbon (e.g., charcoal).

The specific questions related to these allotropes are not visible in the provided image.