![\tt C.~Ka=([H^+][CN^-])/([HCN])](https://img.qammunity.org/2021/formulas/chemistry/high-school/1j2skt64aj3tw4gz4dhhon9fbag69jq6iw.png)
Further explanation
According to Arrhenius, acids are substances which, when dissolved in water, release Hions.
An HₓY acid in water will ionize:
HₓY (aq) ⇒ xH⁺ (aq) + Yˣ- (aq)
In general, the weak acid ionization reaction
HA (aq) ⇒ H⁺ (aq) + A⁻ (aq)
Ka's value
![\large {\boxed {\bold {Ka \: = \: \frac {[H ^ +] [A ^ -]} {[HA]}}}}](https://img.qammunity.org/2021/formulas/chemistry/college/hhnrah3eglzxsrnudjdspk2yngyubne268.png)
So for HCN
HCN(aq)⇒H⁺(aq)+CN⁻(aq)
![\tt Ka=([H^+][CN^-])/([HCN])](https://img.qammunity.org/2021/formulas/chemistry/high-school/lpllynxmcgxfpwrhw6ylj37czrdk124uq0.png)