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

Which of the following solutions does not act as a buffer $:-$

The $pK_a$ of $HCN$ is $9.30$. What is the $pH$ of a solution prepared by mixing $2.5 \ mol$ of $KCN$ and $2.5 \ mol$ of $HCN$ in $500 \ mL$ of water (in $.30$)?

$A$ buffer solution is prepared by mixing $0.01 \ M$ weak acid and $0.05 \ M$ solution of a salt of weak acid and strong base. What is the $pH$ of the buffer solution? $(pK_a = 4.74)$

Study the following table:

Buffer Solution	Volume (in $mL$) of $0.1 \ M$ Weak acid	Volume (in $mL$) of $0.1 \ M$ sodium salt of weak acid
$I$	$4.0$	$4.0$
$II$	$4.0$	$40.0$
$III$	$40.0$	$4.0$
$IV$	$0.1$	$10.0$

Which of the two sets of buffer solutions have the least $pH$?

In some solutions,the concentration of $H_3O^{+}$ remains constant even when small amounts of strong acid or strong base are added to them. These solutions are known as