Question

Which non-metallic solid is known for its electrical conductivity?

• A. Sulfur
• B. Diamond
• C. Graphite
• D. Phosphorus

Hint:

The sp\(_2\) hybridization and delocalized pi electrons in graphite's layered structure are key to its electrical conductivity, distinguishing it from diamond.

Answer 1

The Correct Option is C

Step 1: Consider properties of non-metals.
Most non-metals are electrical insulators. However, there are exceptions to this rule. Step 2: Evaluate each option based on electrical conductivity in the solid state.
(A) Sulfur: Elemental sulfur is a non-metal and is generally a poor conductor of electricity, acting as an insulator.
(B) Diamond: An allotrope of carbon, diamond has a tetrahedral structure where all valence electrons are involved in strong covalent bonds. There are no free electrons, making it an excellent electrical insulator.
(C) Graphite: Another allotrope of carbon, graphite has a layered structure. Each carbon atom in a layer is sp\(_2\) hybridized and bonded to three other carbon atoms. The remaining unhybridized p-orbital on each carbon atom overlaps with p-orbitals of adjacent atoms, forming a delocalized pi electron system above and below the planes of carbon atoms. These delocalized electrons are free to move within the layers, making graphite a good electrical conductor along the layers.
(D) Phosphorus: Different allotropes of phosphorus (white, red, black) exist. While some forms like black phosphorus can be semiconducting, it is not generally known as a good conductor like graphite. Step 3: Conclusion.
Among the given non-metallic solids, Graphite stands out as a well-known conductor of electricity due to its unique bonding and electron delocalization.