Which of the following salts of weak acids and weak bases on hydrolysis turns red litmus blue? [ K_a for acetic acid = 1.8 10⁻⁵ , K_a for hydrofluoric acid = 6.8 10⁻⁴ , K_a for hydrogen cynide = 4.0 10⁻¹⁰ , K_a for formic acid 1.8 10⁻⁴ and K_b for ammonium hydroxide = 1.8 10⁻⁵ ]

Step-by-step solution

A salt of a weak acid and a weak base forms a basic solution if the dissociation constant of the base ( K_b ) is greater than the dissociation constant of the acid ( K_a ). A basic solution turns red litmus blue. For ammonium acetate: K_a = 1.8 10⁻⁵ and K_b = 1.8 10⁻⁵ . Since K_a = K_b , the solution is neutral. For ammonium fluoride: K_a = 6.8 10⁻⁴ and K_b = 1.8 10⁻⁵ . Since K_a > K_b , the solution is acidic. For ammonium cyanide: K_a = 4.0 10⁻¹⁰ and K_b = 1.8 10⁻⁵ . Since K_b > K_a , the solution is basic. For a