Answer: Carbon forms p-p multiple bonds (O=C=O); silicon forms single Si–O network bonds.
- A Carbon forms p-p multiple bonds (O=C=O); silicon forms single Si–O network bonds
- B Carbon cannot form any double bonds
- C Silicon is far more electronegative than carbon and forms pi bonds very easily
- D CO<sub>2</sub> is ionic whereas SiO<sub>2</sub> is covalent
Correct answer: A. Carbon forms p-p multiple bonds (O=C=O); silicon forms single Si–O network bonds
Explanation: Small carbon forms effective p-p pi bonds, allowing discrete O=C=O molecules; silicon forms weak pi bonds so it satisfies its valences with single Si–O sigma bonds in a three-dimensional network solid.
Diamond's rigid 3D tetrahedral network makes it the hardest natural material, while graphite's flat hexagonal sheets are held together only by weak forces, letting them slide past each other (used as a lubricant and in pencils).
Concept context
Covers the Boron family (Group 13: B, Al) and the Carbon family (Group 14: C, Si, Ge, Sn, Pb). Key topics include Lewis acid behaviour of BF₃, borax bead test, silicates, silicones, allotropes of carbon, and trends in properties down the group.