Which one of the following elements is a non-metal but is lustrous ?

Elements are broadly classified into metals and non-metals based on their physical and chemical properties. Metals are typically characterized by their lustrous (shiny) appearance, malleability, and high conductivity [3]. In contrast, non-metals are generally non-lustrous, brittle, and poor conductors of heat and electricity [1]. However, there are specific exceptions to these general rules. While most non-metals like carbon (in coal form) and sulfur are dull, iodine is a notable exception as it is a non-metal that possesses a lustrous, shiny appearance [4]. Silicon and germanium are classified as metalloids or semimetals, which exhibit properties intermediate between metals and non-metals, such as having a metallic luster while being brittle. Therefore, among the given options, iodine is the specific non-metal recognized for its lustrous property.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Table 3.1 > p. 40
2. [3] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.1.2 Non-metals > p. 39
3. [4] Science-Class VII . NCERT(Revised ed 2025) > Chapter 4: The World of Metals and Non-metals > In a Nutshell > p. 54