Answer: an octet using chlorine bridges.
- A an octet using chlorine bridges
- B an incomplete electron sextet still
- C the unstable +1 oxidation state
- D an sp hybridised geometry
Correct answer: A. an octet using chlorine bridges
Explanation: Two chlorine atoms bridge the aluminiums, donating lone pairs so each Al completes its octet in the dimeric Al₂Cl₆ structure.
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.