If $pK_b$ for $CN^{-}$ at $25\,^{\circ}C$ is $3.7$,what is the $pH$ of a $0.5\, M$ aqueous $NaCN$ solution?

$20\,mL$ of $0.1\,M\,NH_{4}OH$ is mixed with $40\,mL$ of $0.05\,M\,HCl$. The $pH$ of the mixture is nearest to. (Given: $K_{b}(NH_{4}OH) = 1 \times 10^{-5}, \log 2 = 0.30, \log 3 = 0.48, \log 5 = 0.69, \log 7 = 0.84, \log 11 = 1.04$) (in $.2$)

Identify the weak acid-weak base salt from the following.

If the value of $K_b$ is $10^{-5}$,find the $K_h$ value for a salt of (strong acid - weak base) at $363 \ K \ (90 \ ^\circ C)$. [At $90 \ ^\circ C, K_w = 10^{-12}$]

Which among the following salts forms a basic solution when dissolved in water?

$0.5 \, M$ ammonium benzoate is hydrolysed to $0.25 \%$ percent,hence its hydrolysis constant is