Answer: Has a small size, high electronegativity and no d-orbitals in its valence shell.
- A Has a small size, high electronegativity and no d-orbitals in its valence shell
- B Has low-lying vacant d-orbitals in its valence shell available for bonding
- C Shows only the lower oxidation state
- D Is always metallic in nature
Correct answer: A. Has a small size, high electronegativity and no d-orbitals in its valence shell
Explanation: The first element (e.g., B, C) is small, more electronegative and lacks valence d-orbitals, so it shows anomalous behaviour compared with the heavier members of its group.
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.