$40 \ mL$ of $0.1 \ M$ ammonia solution is mixed with $20 \ mL$ of $0.1 \ M \ HCl$. What is the $pH$ of the mixture? ($pK_b$ of ammonia solution is $4.74$).

If $20 \ mL$ of $0.1 \ M \ NaOH$ is added to $30 \ mL$ of $0.2 \ M \ CH_3COOH$ $(pK_a = 4.74)$,find the $pH$ of the resulting solution.

An aqueous buffer is prepared by adding $100 \, mL$ of $0.1 \, mol \, L^{-1}$ acetic acid to $50 \, mL$ of $0.2 \, mol \, L^{-1}$ of sodium acetate. If $pK_a$ of acetic acid is $4.76$,the $pH$ of the buffer is

Which of the following acts as a buffer solution?

Which of the following is not a buffer solution?

Calculate the $pH$ of a $0.10 \,M$ ammonia solution. Calculate the $pH$ after $50.0 \,mL$ of this solution is treated with $25.0 \,mL$ of $0.10 \,M$ $HCl$. The dissociation constant of ammonia,$K_{b} = 1.77 \times 10^{-5}$.