| Column-I | Column-II | ||
| (A) | Weak electrolytes | (p) | Electron pair donor |
| (B) | Lewis base | (q) | Partial ionization |
| (C) | pKa | (r) | \(-log K_a\) |
| (D) | Indicator | (s) | Changes color at endpoint |
At what \(\mathrm{pH}\) will the concentrations of a weak acid and its conjugate base be equal, given that the \(\mathrm{p K_a}\) of the acid is 5.85?
1. 6.85
2. 5.85
3. 4.85
4. 7.85