$H{N}_3(aq)+H_{2}O(l)H_3{O}^{+}(aq)+N_3^{-}(aq),K_c=1\mathrm{.}9{10}^{-5}$

The $K_c$ expression for hydroazoic acid is

a$.$

$K_{eq}=\frac{[H{N}_3(aq)]}{[H_3{O}^{+}(aq)][N_3^{**}(aq)]}$

c$.$

$K_{eq}=\frac{[H_3{O}^{+}(aq)][N_3(aq)]}{[H{N}_3(aq)][H_{2}O(l)]}$

b$.K_{eq}=\frac{[H{N}_3(aq)][H_{2}O(l)]}{[H_3{O}^{+}(aq)][N_3*(aq)]}$

d$.K_{eq}=\frac{[H_3{O}^{+}(aq)][N_3*(aq)]}{[H{N}_3(aq)]}$