If $50 \, mL$ of $2 \, N$ acetic acid is mixed with $10 \, mL$ of $1 \, N$ sodium acetate solution,what will be the approximate $pH$ of the resulting solution? (Given: $K_a = 10^{-5}$)

The $pK_a$ of a weak acid is $4.8$. What should be the ratio of $\frac{[\text{acid}]}{[\text{salt}]}$, if a buffer of $pH = 5.8$ is required?

Observe the following four solutions :
$P : 10 \ mL, 0.1 \ M \ NaOH + 5 \ mL, 0.1 \ M \ HCl$
$Q : 10 \ mL, 0.1 \ M \ NaOH + 15 \ mL, 0.1 \ M \ CH_3COOH$
$R : 10 \ mL, 0.1 \ M \ NH_3 + 10 \ mL, 0.1 \ M \ NH_4Cl$
$S : 10 \ mL, 0.05 \ M \ NaF + 5 \ mL, 0.1 \ M \ HF$
Which of above solutions act as buffer?

The $pH$ of the solution containing $50 \ mL$ each of $0.10 \ M$ sodium acetate and $0.01 \ M$ acetic acid is $.......$
[Given $pK_{a}$ of $CH_{3}COOH = 4.57$] (in $.57$)

$A$ certain buffer solution contains equal concentration of $X^{-}$ and $HX$. The $K_b$ for $X^{-}$ is $10^{-10}$. The $pH$ of the buffer is

Aqueous solutions of $HNO_{3}$, $KOH$, $CH_{3}COOH$, and $CH_{3}COONa$ of identical concentration are provided. The pair$(s)$ of solutions which form a buffer upon mixing is (are):