Buffer solutions

At 25 °C, 20.0 mL of 0.2 M weak monoprotic acid HX is titrated against 0.2 M NaOH. The pH of the solution (a) at the start of the titration (when NaOH has not been added) and (b) when 10 mL of NaOH is added respectively, are :
Given : $K_a=5\times10^{-4}$, $pK_a=3.3$, $\alpha\ll1$

The pH of a solution obtained by mixing 5 mL of 0.1 M $\ce{NH4OH}$ solution with 250 mL of 0.1 M $\ce{NH4Cl}$ solution is ________ $\times10^{-2}$. (Nearest integer)
Given: $pK_b(\ce{NH4OH})=4.74$, $\log2=0.30$, $\log3=0.48$, $\log5=0.70$

20 mL of a solution of acetic acid required 28.4 mL of 0.1 M NaOH for its neutralization. A solution (X) was prepared by mixing 20 mL of the above acetic acid and 14.2 mL of 0.1 M NaOH solution. What is the pH of the solution (X)?
($pK_a$ value of acetic acid is 4.75).

A solution is prepared by mixing 0.01 mol each of $\ce{H2CO3}$, $\ce{NaHCO3}$, $\ce{Na2CO3}$, and NaOH in 100 mL of water. $p$H of the resulting solution is _____.

[Given: $pK_{a1}$ and $pK_{a2}$ of $\ce{H2CO3}$ are 6.37 and 10.32, respectively; log 2 = 0.30]

50 mL of 0.1 M $\mathrm{CH_3COOH}$ is being titrated against 0.1 M NaOH. When 25 mL of NaOH has been added, the pH of the solution will be ______ $\times10^{-2}$. (Nearest integer)

(Given : $\mathrm pK_a(\mathrm{CH_3COOH})=4.76$, $\log2=0.30$, $\log3=0.48$, $\log5=0.69$, $\log7=0.84$, $\log11=1.04$)

A student needs to prepare a buffer solution of propanoic acid and its sodium salt with pH 4. The ratio of $\dfrac{\left[\mathrm{CH_3CH_2COO^-}\right]}{\left[\mathrm{CH_3CH_2COOH}\right]}$ required to make buffer is ______.

Given : $K_a\left(\mathrm{CH_3CH_2COOH}\right)=1.3\times10^{-5}$

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

(Given: $\mathrm pK_b(\mathrm{NH_3})=4.74$; Molar mass of $\mathrm{NH_3}$ = 17 g mol$^{-1}$; Molar mass of $\mathrm{NH_4Cl}$ = 53.5 g mol$^{-1}$)

50 mL of 0.1 M CH$_3$COOH is titrated against 0.1 M NaOH solution. When 10 mL of NaOH is added, the pH of the solution becomes _______ $\times10^{-1}$. (nearest integer)

Given: pKa (CH$_3$COOH) = 4.8, log 2 = 0.3

A solution of 0.1 M weak base (B) is titrated with 0.1 M of a strong acid (HA). The variation of pH of the solution with the volume of HA added is shown in the figure below. What is the p$K_b$ of the base? The neutralization reaction is given by $\ce{B + HA -> BH+ + A-}$.

Dilution processes of different aqueous solutions, with water, are given in LIST-I. The effects of dilution of the solutions on $[\mathrm{H^+}]$ are given in LIST-II.

(Note: Degree of dissociation ($\alpha$) of weak acid and weak base is $\ll 1$; degree of hydrolysis of salt $\ll 1$; $[\mathrm{H^+}]$ represents the concentration of $\mathrm{H^+}$ ions)

Match each process given in LIST-I with one or more effect(s) in LIST-II. The correct option is

Addition of sodium hydroxide solution to a weak acid (HA) results in a buffer of pH 6. If ionisation constant of HA is $10^{-5}$, the ratio of salt to acid concentration in the buffer solution will be :

50 mL of 0.2 M ammonia solution is treated with 25 mL of 0.2 M HCl. If $pK_b$ of ammonia solution is 4.75, the pH of the mixture will be :

The pH of the solution after Expt. 2 is

In some solutions, the concentration of $\ce{H3O+}$ remains constant even when small amounts of strong acid or strong base are added to them. These solutions are known as :

Aqueous solutions of $\ce{HNO3}$, KOH, $\ce{CH3COOH}$, and $\ce{CH3COONa}$ of identical concentrations are provided. The pair(s) of solutions which form a buffer upon mixing is(are)