$A$ buffer solution contains $0.1 \ M$ of acetic acid and $0.1 \ M$ of sodium acetate. What will be its $pH$,if $pK_a$ of acetic acid is $4.75$?

Which of the following mixtures in water acts as a buffer?

$A$ 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 $5.00$?

$A$ buffer solution with $pH = 9$ is prepared by mixing $NH_4Cl$ and $NH_4OH$. Calculate the number of moles of $NH_4Cl$ dissolved in $1.0 \, L$ of $1.0 \, M \, NH_4OH$ solution. (Given: $K_b(NH_4OH) = 1.8 \times 10^{-5}$)

What volume (in $mL$) of $0.10 \, M$ sodium formate is required to be added to $50 \, mL$ of $0.05 \, M$ formic acid to prepare a buffer solution with $pH = 4.0$? (Given: $pK_a$ of formic acid $= 3.7$)

Which statement is correct for a mixture of $1 \ M \ NaCl$ and $1 \ M \ HCl$?