For the equilibrium that exists in an aqueous solution of nitrous acid (HNO2, a weak acid), the equilibrium constant expression is:
a) K = [H⁺] [NO₂⁻]/[HNO₂]
b) K = [H⁺] [N] [O]²/ [HNO₂]
c) K = [H⁺] [NO₂⁻]/ [HNO₂]
d) K = [H⁺]² [NO₂⁻]/ [HNO₂]
e) none of these
