If the $pH$ of a buffer solution containing $0.1 \ M$ of monoacidic base and $0.01 \ M$ of its salt is $10.5$,the $pK_a$ of the conjugate acid is: (in $.5$)

Which of the following does not act as a buffer solution?

$A$ buffer solution contains $1 \ mol$ of ammonium sulphate and $1 \ mol$ of $NH_4OH$ $(K_b = 10^{-5})$. The $pH$ of the solution will be:

The $pH$ of a buffer solution decreases by $0.02$ units when $0.12 \ g$ of acetic acid is added to $250 \ mL$ of a buffer solution of acetic acid and potassium acetate at $27^{\circ} C$. The buffer capacity of the solution is

$0.1 \ M$ $CH_3COOH$ is titrated against $0.1 \ M$ $NaOH$. What would be the difference in $pH$ between $1/4$ and $3/4$ stages of neutralization of the acid?

Class $XII$ students were asked to prepare one litre of buffer solution of $pH$ $8.26$ by their chemistry teacher. The amount of ammonium chloride to be dissolved by the student in $0.2 \, M$ ammonia solution to make one litre of the buffer is $..... \, g$ (Given $pK_b(NH_3)=4.74$; Molar mass of $NH_3=17 \, g \, mol^{-1}$; Molar mass of $NH_4Cl =53.5 \, g \, mol^{-1}$)