Values of dissociation constant, Ka are given as follows.
| Acid | Ka |
| HCN | 6.2 × 10−10 |
| HF | 7.2 × 10−4 |
| HNO2 | 4.0 × 10−4 |
Correct order of increasing base strength of the base CN−, F − and \(\rm NO_2^ -\) will be :
1
\(\mathrm{F}<\mathrm{CN}^{-}<\mathrm{NO}_{2}^{-} \)
2
\(\mathrm{NO}_{2}^{-}<\mathrm{CN}^{-}<\mathrm{F}^{-} \)
3
\(\mathrm{F}<\mathrm{NO}_{2}^{-}<\mathrm{CN}^{-} \)
4
\(\mathrm{NO}_{2}^{-}<\mathrm{F}^{-}<\mathrm{CN}^{-}\)