Find the concentration of sodium acetate when added to $0.1 \ M$ solution of acetic acid to form a buffer solution of $pH = 5.5$ (in $M$)? $(pK_{a} \text{ of } CH_{3}COOH = 4.5)$

$20 \ mL$ solution contains $0.1 \ M \ NH_4Cl$ and $0.01 \ M \ NH_4OH$. By adding which one will its $pH$ not change?

The $pH$ of blood is maintained by a proper balance of $H_2CO_3$ and $NaHCO_3$ concentrations. What volume of $5 \, M \, NaHCO_3$ solution should be mixed with $10 \, mL$ of $2 \, M \, H_2CO_3$ to maintain a $pH$ of $7.4$ (in $, mL$)? (Given: $K_a$ for $H_2CO_3 = 7.8 \times 10^{-7}$)

What is the total number of buffers formed during the titration of $H_3PO_4$ with $NaOH$?

The ionization constant $(K_a)$ of a certain weak acid is $10^{-4}$. What should be the $[salt]$ to $[acid]$ ratio if we have to prepare a buffer with $pH = 5$ using this acid and one of its salts?

$50 \ mL$ of $2 \ N$ acetic acid mixed with $10 \ mL$ of $1 \ N$ sodium acetate solution will have an approximate $pH$ of: