$20 \ mL$ of $0.1 \ M \ H_2SO_4$ is added to $30 \ mL$ of $0.2 \ M \ NH_4OH$ solution. The $pH$ of the resultant mixture is [$pK_b$ of $NH_4OH = 4.7$].

The $pOH$ of a basic buffer (e.g.,$NH_4OH/NH_4Cl$) is $5$. If the concentration of the salt is tripled while the concentration of the base remains constant,find the new $pOH$ value. (Given: $\log 3 = 0.48$)

In a mixture of a weak acid and its salt,the ratio of concentration of acid to salt is increased ten-fold. The $pH$ of the solution

The $pH$ of the blood buffer $CO_2-HCO_3^-$ is $7.4$. The ratio of conjugate base to acid is ....... $(K_a (H_2CO_3) = 4.5 \times 10^{-7})$

$A$ buffer solution can be prepared from a mixture of

Which one of the following pairs of solutions is not an acidic buffer?