Question

Generally, non-metals are not lustrous. Which of the following nonmetal is lustrous?

• A. Sulphur
• B. Oxygen
• C. Nitrogen
• D. Iodine

Answer 1

The correct option is D

Iodine

The explanation for the correct option:

Option (D): Iodine

1. Metals have lustre, which indicates how much or how well the metal reflects light.
2. A solid's surface normally exhibits lustre by reflecting incident light. Most nonmetals lack crystalline surfaces and are not completely solid. Since non-metals do not satisfy this condition, they do not exhibit lustre except for Iodine and diamond.
3. Iodine is present in $5\mathrm{th}$ period and in$17\mathrm{th}$ the group of the periodic table. The size of the atoms increases and more shells are added as we move down the group. Therefore, the force of the nucleus on the valence electron of iodine decreases due to the presence of inner shell electrons which results in a lower effective nuclear charge and looser electron bonds.
4. When these electrons absorb light or heat, the de-excitation of the absorbed heat from the surroundings emits light, creating the appearance that the surface is lustrous. Thus making Iodine lustrous.
5. Sulphur, oxygen and nitrogen are non-metals and cannot reflect light due to the absence of their crystalline surface, they are non-lustrous.
6. Hence, it is the correct option.

Therefore, Iodine is a non-metal that is lustrous.