One litre of an aqueous solution contains $0.15 \ mol$ of $CH_3COOH$ $(pK_a = 4.8)$ and $0.15 \ mol$ of $CH_3COONa$. After the addition of $0.05 \ mol$ of solid $NaOH$ to this solution,the $pH$ will be:

An acidic buffer solution can be prepared by mixing the solution of

$A$ sample of $100 \ mL$ of $0.10 \ M$ acid $HA$ $(K_a = 1 \times 10^{-5})$ is titrated with standard $0.2 \ M \ KOH$. How many $mL$ of $KOH$ will have to be added when the $pH$ in the titration flask will be $5.00$?

Aqueous solutions of $HNO_3$,$KOH$,$CH_3COOH$,and $CH_3COONa$ of identical concentrations are provided.
The pair$(s)$ of solutions which form a buffer upon mixing is(are):
$A$. $HNO_3$ and $CH_3COOH$
$B$. $KOH$ and $CH_3COONa$
$C$. $HNO_3$ and $CH_3COONa$
$D$. $CH_3COOH$ and $CH_3COONa$

The $pH$ of a buffer solution containing $25 \ mL$ of $1 \ M \ CH_3COONa$ and $25 \ mL$ of $1 \ M \ CH_3COOH$ will be appreciably affected by $5 \ mL$ of

How many $mL$ of $0.2 \, M \, KCN$ should be mixed with $200 \, mL$ of $0.1 \, M \, HCN$ so as to make a mixture of $pH = 3$ ($pK_a$ for $HCN = 6$)?