In which of the following equilibrium K_c and K_p are not equal?

The dissociation constants for acetic acid and HCN at 25^oC are 1.5 $$ \times $$ 10^$$-$$5 and 4.5 $$ \times $$ 10^$$-$$10 respectively. The equilibrium constant for the equilibrium
CN^$$-$$ + CH₃COOH $$\rightleftharpoons$$ HCN + CH₃COO^$$-$$ would be

The dissociation equilibrium of a gass AB₂ can be represented as :
2AB_2(g) $$\rightleftharpoons$$ 2AB_(g) + B_2(g)
The degree of dissociation is x and is small compared to 1. The expression relating the degree of dissociation (x) with equilibrium constant K_p and total pressure P is

If the concentration of OH^$$-$$ ions in the reaction
Fe(OH)_3(s) $$\rightleftharpoons$$ Fe³⁺_(aq) + 3OH^$$-$$_(aq)
is decreased by 1/4 times, then equilibrium concentration of Fe³⁺ will increase by