Henderson's equation is $pH = pK_a + \log\frac{[\text{salt}]}{[\text{acid}]}$. If the acid is half-neutralized,the value of $pH$ will be: $[pK_a = 4.30]$

Which of the following is a buffer solution?

$50 \, mL$ of $0.1 \, M \, CH_3COOH$ is being titrated against $0.1 \, M \, NaOH$. When $25 \, mL$ of $NaOH$ has been added,the $pH$ of the solution will be $.... \times 10^{-2}$. (Nearest integer)
(Given : $pK_a(CH_3COOH) = 4.76$)
$\log 2 = 0.30$,$\log 3 = 0.48$,$\log 5 = 0.69$,$\log 7 = 0.84$,$\log 11 = 1.04$

$A$ buffer solution is prepared with a concentration of $0.30 \ M \ NH_3$ and $0.20 \ M \ NH_4^+$. If the equilibrium constant for $NH_3$ is $K_b = 1.8 \times 10^{-5}$,what will be the $pH$ of this solution?

In order to prepare a buffer solution of $pH = 5.74$,sodium acetate is added to acetic acid. If the concentration of acetic acid in the buffer is $1.0 \ M$,the concentration of sodium acetate in the buffer is $......... \ M$. (Round off to the nearest integer).
[Given: $pKa$ (acetic acid) $= 4.74$]

Calculate the $pH$ of a $0.10 \,M$ ammonia solution. Calculate the $pH$ after $50.0 \,mL$ of this solution is treated with $25.0 \,mL$ of $0.10 \,M$ $HCl$. The dissociation constant of ammonia,$K_{b} = 1.77 \times 10^{-5}$.