The strength of an acid is inversely related to the strength of its conjugate base.
• Strong acids dissociate completely, producing stable conjugate bases with little tendency to accept a proton. Therefore statement (A) is correct, that is, the stronger the acid, the weaker is the conjugate base.
• pKa value: is the indicator of acid strength; the larger the pKa value, the weaker the acid.
Therefore a higher pKa indicates a weaker acid, which leads to a stronger conjugate base and statement (D) is correct, that is, the larger the pKa value of the conjugate acid, the stronger its base. Statements B and C are incorrect.
| 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) \(a = b \neq c, \alpha = \beta = 90^\circ, \gamma = 120^\circ\) |