Generally non-metals are non-lustrous except

Except for iodine (I), all other non-metals are non-lustrous.

In general, non-metals are known for being non-lustrous (lacking shine) because they do not have free electrons in their outermost shells. This absence of free-moving electrons prevents the reflection of light that gives materials their lustrous appearance. Non-metals, such as chlorine, carbon, and bromine, do not exhibit lustrous properties in their solid state.

Why is Iodine Different?

Iodine (I), however, is an exception among non-metals. Unlike most other non-metals, iodine crystals exhibit a shiny, lustrous appearance. The lustrous property of iodine is due to its unique molecular structure, which allows the reflection of light. Even though iodine is a non-metal, its crystalline form has the capability to reflect light, which is why it is considered a lustrous non-metal.

The only non-metal in the provided options that is lustrous is iodine. Therefore, iodine stands out as an exception among non-metals in terms of having lustrous properties.