Answer: non-polar alkyl groups.
- A polar hydroxyl groups
- B non-polar alkyl groups
- C ionic surface charges
- D freely moving metal ions
Correct answer: B. non-polar alkyl groups
Explanation: The organic alkyl groups on the silicon–oxygen backbone are non-polar, making silicones water-repellent.
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.