Q4 / 150 · MHT CET 2025 (21 Apr Shift 2) · Chemistry

What different types of bonds are formed by chlorine with oxygen in perchloric acid?

  • A
    2-single bonds and 2-double bonds
  • B
    3 -single bonds and 1-double bond
  • C
    2-single bonds and 3-double bonds
  • Correct answer
    D
    1 -single bond and 3-double bonds

Solution

Perchloric acid structure: Chlorine acts as the central atom bonded to four oxygen atoms, with one oxygen also bonded to hydrogen.

Total valence electrons: H (1) + Cl (7) + 4×O (24) = 32.

Initial bonding uses 5 bonds (Cl-O and O-H), consuming 10 electrons.
Remaining 22 electrons distribute as lone pairs: terminal O-H oxygen receives 2 pairs, three Cl-O oxygens each receive 3 pairs.

Formal charges reveal instability: Cl (+3), three oxygens (-1) each. Minimizing charges by converting lone pairs to bonds yields the optimal structure.

Final configuration shows chlorine bonded via:
• One single bond to oxygen in O-H group
• Three double bonds to remaining oxygen atoms

$\text{FC}_{\text{Cl}} = 7 - 0 - \frac{1}{2}(2 + 3\times4) = 0$
$\text{FC}_{\text{O}} = 6 - 4 - \frac{1}{2}(4) = 0$ for double-bonded oxygens

Thus chlorine forms one single bond and three double bonds with oxygen.

Hence, the correct answer is option: 'D'.

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