Equal volumes of $0.5 \ N$ acetic acid and $0.5 \ N$ sodium acetate are mixed. What is the $pH$ of the resultant solution? $(pK_{a}$ of acetic acid $= 4.75)$

Which of the following is not a buffer solution?

One litre of an aqueous solution contains $0.15 \ mol$ of $CH_3COOH$ $(pK_a = 4.8)$ and $0.15 \ mol$ of $CH_3COONa$. After the addition of $0.05 \ mol$ of solid $NaOH$ to this solution,the $pH$ will be:

$A$ buffer solution is prepared by mixing $0.2 \ M \ NH_4OH$ and $1 \ M \ NH_4Cl$. What is the $pH$ value of the buffer solution? (Given $pK_b = 4.744$)

What is the $pH$ of the solution obtained by mixing $5.076 \ g$ of methyl ammonium nitrate $(CH_3NH_3NO_3)$ into $120 \ mL$ of $0.225 \ M$ methylamine $(CH_3NH_2$; $K_b = 4 \times 10^{-4})$?

$100 \ mL$ of a solution contains $0.1 \ M$ $NH_4OH$ and $0.1 \ M$ $NH_4Cl$. The $pH$ of the solution will not change on adding :-