The correct option is Iodine.
Explanation
Non-metals are generally characterized by physical properties that contrast with metals. One defining characteristic is that non-metals are typically non-lustrous, meaning they have a dull appearance and do not reflect light to create a shine. However, there are specific exceptions to this general rule found in nature.
Detailed Analysis
- Iodine: Although it is a non-metal, Iodine exists as a solid at room temperature and possesses a distinct metallic lustre. Its crystals appear shiny and violet-black, making it a primary exception to the non-lustrous nature of non-metals.
- Sulphur and Phosphorus: These are typical solid non-metals that appear dull and opaque, adhering to the general property of lacking lustre.
- Nitrogen: This exists as a gas at room temperature and does not exhibit surface lustre.
Key Takeaway: While most non-metals are dull, Iodine and Graphite (an allotrope of Carbon) are notable exceptions that exhibit a shiny, lustrous appearance.