In a mixture of a weak acid and its salt,the ratio of concentration of acid to salt is increased ten-fold. The $pH$ of the solution

$A$ buffer solution contains $0.1 \ mol$ of sodium acetate in $1000 \ cm^{3}$ of $0.1 \ M$ acetic acid. To the above buffer solution,$0.1 \ mol$ of sodium acetate is further added and dissolved. The $pH$ of the resulting buffer is equal to

$3 \; g$ of acetic acid is added to $250 \; mL$ of $0.1 \; M \; HCl$ and the solution is made up to $500 \; mL$. To $20 \; mL$ of this solution,$\frac{1}{2} \; mL$ of $5 \; M \; NaOH$ is added. The $pH$ of the solution is: [Given: $pK_{a}$ of acetic acid $= 4.75$,molar mass of acetic acid $= 60 \; g/mol$,$\log 3 = 0.4771$]. Neglect any changes in volume.

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) $= 4.74$]

Which buffer is present in human blood :-

For preparing a buffer solution of $pH = 5$ by mixing sodium acetate and acetic acid,the ratio of the concentration of salt and acid should be $(K_a = 10^{-5})$:-