An acidic buffer solution is prepared by mixing a proportionate quantity of

The buffer system which helps to maintain the $pH$ of blood between $7.26$ to $7.42$ is:

If $12.5 \ mL$ of $0.1 \ M$ $KOH$ is added into $50 \ mL$ of $0.1 \ M$ $CH_3COOH$ solution,then what would be the final $pH$? $(K_a(CH_3COOH) = 2 \times 10^{-5})$

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 dissociation constant of $HCN$ is $5 \times 10^{-10}$. The $pH$ of the solution prepared by mixing $1.5 \, mole$ of $HCN$ and $0.15 \, mole$ of $KCN$ in water and making up the total volume to $0.5 \, dm^3$ is (in $.302$)

When a buffer solution of sodium acetate and acetic acid is diluted with water,