Which of the following will not undergo hydrolysis in water?

$pH$ of a salt solution of weak acid $(pK_a = 4)$ and weak base $(pK_b = 5)$ at $25^{\circ}C$ is:

When $C_6H_5NH_3^+ Cl^-$ salt is dissolved in water,it undergoes hydrolysis. Find the equilibrium constant of the hydrolysis reaction if the ionization constant of the weak base is $10^{-4}$.

Find out $K_a$ for the acid when the degree of hydrolysis of $0.1 \ M \ CH_3COONa$ is $1 \ \%$.

Which among the following salts turns red litmus blue in its aqueous solution?

$A$ white substance having alkaline nature in solution is