The acidic strength of oxoacids increases with the number of oxygen atoms attached to the central atom. This is because more oxygen atoms stabilize the conjugate base through resonance.
• HOCl has one oxygen atom
• HOClO has two oxygen atoms
• HOClO2 has three oxygen atoms
• HOClO3 has four oxygen atoms.
The order of increasing acid strength is HOCl <HOClO <HOClO2 <HOClO3. The higher the number of oxygen atoms, the greater the resonance and stabilization of the conjugate base, and thus a stronger acid.
| List-I (System) | List-II (Axial lengths and angles) |
|---|---|
| (A) Cubic | (I) \(a = b = c, \alpha = \beta = \gamma = 90^\circ\) |
| (B) Tetragonal | (II) \(a = b \neq c, \alpha = \beta = \gamma = 90^\circ\) |
| (C) Orthorhombic | (III) \(a \neq b \neq c, \alpha = \beta = \gamma = 90^\circ\) |
| (D) Hexagonal | (IV) \(a = b \neq c, \alpha = \beta = 90^\circ, \gamma = 120^\circ\) |