Chapter 8

\(0.1 \mathrm{M}\) solution of three different sodium salts NaX, NaY and \(\mathrm{NaZ}\) have \(\mathrm{pH}\) values \(7.0,9.0\) and \(11.0\) respectively. The correct order of dissociation constant values of these acids is (a) \(\mathrm{K}_{\mathrm{HX}}<\mathrm{K}_{\mathrm{HY}}<\mathrm{K}_{\mathrm{HZ}}\) (b) \(\mathrm{K}_{\mathrm{HX}}>\mathrm{K}_{\mathrm{HY}}>\mathrm{K}_{\mathrm{Hz}}\) (c) \(\mathrm{K}_{\mathrm{HX}}>\mathrm{K}_{\mathrm{Hz}}>\mathrm{K}_{\mathrm{HY}}\) (d) \(\mathrm{K}_{\mathrm{Hx}}<\mathrm{K}_{\mathrm{HY}}<\mathrm{K}_{\mathrm{Hz}}\)

When equal volume of the following solutions are mixed, which of the following gives maximum precipitate? \(\left(\mathrm{K}_{s p}\right.\) of \(\left.\mathrm{AgCl}=10^{-12}\right)\) (a) \(10^{-4} \mathrm{M} \mathrm{Ag}^{+}\)and \(10^{-4} \mathrm{M} \mathrm{Cl}^{-}\) (b) \(10^{-3} \mathrm{M} \mathrm{Ag}^{+}\)and \(10^{-3} \mathrm{M} \mathrm{Cl}^{-}\) (c) \(10^{-5} \mathrm{M} \mathrm{Ag}^{+}\)and \(10^{-5} \mathrm{M} \mathrm{Cl}^{-}\) (d) \(10^{-6} \mathrm{M} \mathrm{Ag}^{+}\)and \(10^{-6} \mathrm{M} \mathrm{Cl}^{-}\)

The percentage hydrolysis of \(\mathrm{NaCN}\) in \(\left(\frac{\mathrm{N}}{80}\right)\) aqueous solution [Dissociation constant of \(\mathrm{HCN}\) is \(1.3 \times 10^{-9}\) and \(\left.\mathrm{K}_{\mathrm{w}}=1.0 \times 10^{-14}\right]\) is (a) \(8.2\) (b) \(9.6\) (c) \(5.26\) (d) \(2.48\)

Hydrolysis constant \(\mathrm{K}_{\mathrm{A}}\) and \(\mathrm{K}_{\mathrm{B}}\) of two salts of weak acids HA and \(\mathrm{HB}\) are \(10^{-8}\) and \(10^{-6}\) respectively. If the dissociation constant of third acid \(\mathrm{HC}\) is \(10^{-2} .\) The order of acidic strengths of three acids will be (a) \(\mathrm{HA}>\mathrm{HB}>\mathrm{HC}\) (b) \(\mathrm{HB}>\mathrm{HA}>\mathrm{HC}\) (c) \(\mathrm{HC}>\mathrm{HA}>\mathrm{HB}\) (d) \(\mathrm{HA}=\mathrm{HB}=\mathrm{HC}\)

A solution containing \(\mathrm{NH}_{4} \mathrm{Cl}\) and \(\mathrm{NH}_{4} \mathrm{OH}\) has a hydroxide ion concentration of \(10^{-6} \mathrm{~mol}\) litre \(^{-1}\), which of the following hydroxides could be precipitated when this solution is added in equal volume to a solution containing \(0.1 \mathrm{M}\) of metal ions? (a) \(\mathrm{AgOH}\left(\mathrm{K}_{\mathrm{sp}}=5 \times 10^{-3}\right)\) (b) \(\mathrm{Cd}(\mathrm{OH})_{2}\left(\mathrm{~K}_{s p}=8 \times 10^{-6}\right)\) (c) \(\mathrm{Mg}(\mathrm{OH})_{2}\left(\mathrm{~K}_{\mathrm{sp}}=3 \times 10^{-11}\right)\) (d) \(\mathrm{Fe}(\mathrm{OH})_{3}\left(\mathrm{~K}_{\mathrm{sp}}=8 \times 10^{-16}\right)\)

In the precipitation titration of \(\mathrm{KCl}\) against \(\mathrm{AgNO}_{3}\), \(\mathrm{K}_{2} \mathrm{CrO}_{4}\) is used as an indicator since, \(\mathrm{AgCl}\) is white coloured. End point is detected by appearance of deep yellow coloured precipitate of \(\mathrm{Ag}_{2} \mathrm{CrO}_{4}\). The minimum concentration of chromate ion required for detection of end point is \(\left[\mathrm{K}_{\mathrm{sp}}\right.\) of \(\mathrm{AgCl}=2.5 \times 10^{-10}\) and \(\mathrm{K}_{\mathrm{sp}}\) of \(\left.\mathrm{Ag}_{2} \mathrm{CrO}_{4}=1.8 \times 10^{-12}\right]\) (a) \(7.3 \times 10^{-2} \mathrm{M}\) (b) \(5.3 \times 10^{-4} \mathrm{M}\) (c) \(7.3 \times 10^{-3} \mathrm{M}\) (d) \(3.6 \times 10^{-5} \mathrm{M}\)

The concentration of hydroxyl ion in a solution left after mixing \(100 \mathrm{~mL}\) of \(0.1 \mathrm{M} \mathrm{MgCl}_{2}\) and \(100 \mathrm{~mL}\) of \(0.2 \mathrm{M} \mathrm{NaOH}\left[\mathrm{K}_{\mathrm{sp}}\right.\) of \(\left.\mathrm{Mg}(\mathrm{OH})_{2}=1.2 \times 10^{-11}\right]\) is (a) \(2.8 \times 10^{-3}\) (b) \(2.8 \times 10^{-2}\) (c) \(2.8 \times 10^{-4}\) (d) \(2.8 \times 10^{-5}\)

When \(0.1 \mathrm{~mol}\) of \(\mathrm{CH}_{3} \mathrm{NH}_{2}\left(\mathrm{~K}_{\mathrm{b}}=5 \times 10^{-4}\right)\) is mixed with \(0.08 \mathrm{~mol}\) of \(\mathrm{HCl}\) and diluted to \(1 \mathrm{~L}\), the \(\mathrm{H}^{+}\)ion concentration in the solution is (a) \(8 \times 10^{-11} \mathrm{M}\) (b) \(6 \times 10^{-5} \mathrm{M}\) (c) \(1.6 \times 10^{-11} \mathrm{M}\) (d) \(8 \times 10^{-2} \mathrm{M}\)

When \(\mathrm{H}_{2} \mathrm{~S}\) is passed through an aqueous solution of an equilimolar mixture of \(\mathrm{Zn}^{2+}\) and \(\mathrm{Pb}^{2+}\) acidified with dilute acetic acid, \(\mathrm{ZnS}\) is not precipitated, because (a) \(\mathrm{K}_{\mathrm{s}}(\mathrm{ZnS})<\mathrm{K}_{\mathrm{si}}(\mathrm{PbS})\) (b) \(\mathrm{K}_{\mathrm{ss}}(\mathrm{ZnS})>\mathrm{K}_{s p}(\mathrm{PbS})\) (c) \(\mathrm{H}_{2} \mathrm{~S}\) decreases the \(\mathrm{K}_{\text {sp }}\) of \(\mathrm{ZnS}\) (d) \(\mathrm{H}_{2} \mathrm{~S}\) increases the \(\mathrm{K}_{\text {p }}\) of \(\mathrm{PbS}\)

When equal volumes of the following solutions are mixed, the precipitation of \(\mathrm{AgCl}\left(\mathrm{K}_{s p}=1.8 \times 10^{-10}\right)\) will occur with (a) \(10^{-5} \mathrm{M}\left(\mathrm{Ag}^{+}\right)\)and \(10^{-3} \mathrm{M}\left(\mathrm{Cl}^{-}\right)\) (b) \(10^{-4} \mathrm{M}\left(\mathrm{Ag}^{+}\right)\)and \(10^{-4} \mathrm{M}\left(\mathrm{Cl}^{-}\right)\) (c) \(10^{-5} \mathrm{M}\left(\mathrm{Ag}^{+}\right)\)and \(10^{-1} \mathrm{M}\left(\mathrm{Cl}^{-}\right)\) (d) \(10^{-5} \mathrm{M}\left(\mathrm{Ag}^{+}\right)\)and \(10^{-5} \mathrm{M}\left(\mathrm{Cl}^{-}\right)\)

Mark the correct statements (a) \(\mathrm{pK}_{\mathrm{a}}+\mathrm{pK}_{\mathrm{b}}=\mathrm{pK}_{\mathrm{w}}\), at all temperatures. (b) Acetic acid behaves like a strong acid in \(\mathrm{NH}_{3}\). (c) \(\mathrm{H}_{3} \mathrm{O}^{+}\)is a strong nucleophile (d) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}\)is a weaker base than \(\mathrm{OH}^{-}\).

Which of the following statements is/are correct about the ionic product of water ? (a) At \(25^{\circ} \mathrm{C}, \mathrm{K}\) (dissociation constant of water \()>\mathrm{K}_{\mathrm{w}}\) (ionic product of water) (b) \(K_{w}\) of boiling water is greater than \(10^{-14}\). (c) Ionic product of water at \(25^{\circ} \mathrm{C}\) is \(10^{-14}\) (d) \(\mathrm{pH}+\mathrm{pOH}=\mathrm{pK}_{\mathrm{w}^{\circ}}\)

If molar concentrations of two weak acids are the same, their relative strengths can be compared by (a) \(\frac{\alpha_{1}}{\alpha_{2}}\) (b) \(\frac{\mathrm{K}_{1}}{\mathrm{~K}_{2}}\) (c) \(\sqrt{\mathrm{K}_{1} / \mathrm{K}_{2}}\) (d) \(\frac{\left[\mathrm{H}^{+}\right]_{1}}{\left[\mathrm{H}^{+}\right]_{2}}\)

Which of the following are the correct statements (a) The \(\mathrm{pH}\) of blood is same in summer and winter (b) \(\mathrm{pH}\) of an acidic buffer increases if more salt is added (c) \(\mathrm{pH}\) of a basic buffer decreases if more salt is added (d) The term solubility product is only for sparingly soluble salts

Which of the following statements are correct? (a) The conjugate base of \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)is \(\mathrm{HPO}_{4}^{2-}\) (b) \(\mathrm{pH}\) of \(1.0 \times 10^{-8} \mathrm{M}\) aqueous solution of \(\mathrm{HCl}\) is 8 . (c) When a weak monoprotic acid solution is treated with a strong base, at half neutralization point, $$ \mathrm{pH}=\frac{1}{2} \mathrm{pK}_{\mathrm{a}} $$ (d) The autoprotolysis constant of water increases with temperature.

Which of the following solutions will have no effect on \(\mathrm{pH}\) on dilution? (a) \(0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONa}\) (b) \(1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONH}_{4}\) (c) \(0.1 \mathrm{M} \mathrm{NH}_{4} \mathrm{OH}+0.1 \mathrm{M} \mathrm{NH}_{4} \mathrm{Cl}\) (d) \(0.5 \mathrm{M} \mathrm{H}_{2} \mathrm{CO}_{2}+0.5 \mathrm{M} \mathrm{NaHCO}_{3}\)

A buffer solution can be prepared from a mixture of (a) \(\mathrm{CH}_{3} \mathrm{COONa}\) and \(\mathrm{CH}_{3} \mathrm{COOH}\) in water (b) \(\mathrm{CH}_{3} \mathrm{COONa}\) and \(\mathrm{HCl}\) in water under certain conditions (c) \(\mathrm{NH}_{4} \mathrm{OH}\) and \(\mathrm{NH}_{4} \mathrm{Cl}\) in water (d) \(\mathrm{NaCl}\) and \(\mathrm{HCl}\) in water

Which of the following solution in water act as buffer? (a) \(0.5\) mol of pyridine \(+0.5 \mathrm{~mol}\) of Pyridinium chloride (b) \(0.1 \mathrm{~mol}\) of \(\mathrm{NaOH}+0.15 \mathrm{~mol}\) of \(\mathrm{CH}_{3} \mathrm{COOH}\) (c) \(\mathrm{CH}_{3} \mathrm{COONH}_{4}\) (d) \(0.25 \mathrm{~mol}\) of \(\mathrm{NH}_{4} \mathrm{Cl}+0.5 \mathrm{~mol}\) of \(\mathrm{NaOH}\).

Which of the following are wrong statements? (a) \(\mathrm{K}_{\mathrm{i}}\) is always constant and equal to \(10^{-14}\) (b) \(\mathrm{pH}+\mathrm{pOH}=\mathrm{pK}_{w}\) at all temperature (c) Salts of strong acid and strong base undergo hydrolysis (d) Addition of \(\mathrm{CH}_{3} \mathrm{COONa}\) to acetic acid solution decreases the \(\mathrm{pH}\) of solution of acetic acid.

Equal volumes of \(\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}\) (c M) solution of \(\mathrm{pH}=5\) is mixed with \(\mathrm{HCl}\) solution of same \(\mathrm{pH}\). Which of the following is an incorrect statement? (a) Concentration of \(\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}\) will become \(\mathrm{c} / 2 \mathrm{M}\) after mixing HCl with it. (b) Concentration of \(\mathrm{H}^{+}\)after mixing the two solutions is \(10^{-5} \mathrm{M}\) (c) The degree of dissociation of \(\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}\) is suppressed due to addition of \(\mathrm{HCl}\). (d) Original concentration of \(\mathrm{HCl}\) was \(10^{-5} \mathrm{M}\).

The solubility product of \(\mathrm{AgCl}\) is \(1.8 \times 10^{-10}\) at \(298 \mathrm{~K}\). The solubility of \(\mathrm{AgCl}\) in \(0.01 \mathrm{M} \mathrm{HCl}\) solution is (a) \(1.8 \times 10^{-8} \mathrm{M}\) (b) \(1.4 \times 10^{-6} \mathrm{M}\) (c) \(1.8 \times 10^{-6} \mathrm{M}\) (d) \(1.4 \times 10^{-4} \mathrm{M}\)

Three sparingly soluble salts \(\mathrm{M}_{2} \mathrm{~B}, \mathrm{MB}\) and \(\mathrm{MB}_{3}\) have the same solubility product. Their solubilities will be in the order (a) \(\mathrm{MB}_{3}>\mathrm{M}_{2} \mathrm{~B}>\mathrm{MB}\) (b) \(\mathrm{MB}>\mathrm{M}_{2} \mathrm{~B}>\mathrm{MB}_{3}\) (c) \(\mathrm{MB}_{3}>\mathrm{MB}>\mathrm{M}_{2} \mathrm{~B}\) (d) \(\mathrm{MB}>\mathrm{MB}_{3}>\mathrm{M}_{2} \mathrm{~B}\)

The \(\mathrm{pH}\) of the solution at phenolphthalein end point would be (Given \(\mathrm{pK}_{2}\) ) and \(\mathrm{pK}_{\mathrm{a}_{2}}\) of carbonic acid are \(6.34\) and \(10.34\) ) respectively. (a) \(4.43\) (b) \(5.34\) (c) \(8.34\) (d) \(11.34\)

\(50 \mathrm{~mL}\) of \(0.1 \mathrm{M}\) aqueous \(\mathrm{NaOH}\) is mixed with \(10 \mathrm{~mL}\) of \(0.1 \mathrm{M}\) aqueous acetic acid. The conc. \(\left(\mathrm{OH}^{-}\right)\)of resulting solution is (a) \(0.04 \mathrm{M}\) (b) \(0.080 \mathrm{M}\) (c) \(0.0607 \mathrm{M}\) (d) \(0.0667 \mathrm{M}\)

\(50 \mathrm{~mL}\) of \(0.2 \mathrm{M}\) aqueous \(\mathrm{CH}_{3} \mathrm{COOH}\) is mixed with \(50 \mathrm{~mL}\) of \(0.2 \mathrm{M}\) aqueous KOH solution. The \(\mathrm{pH}\) of resulting solution is \(\left(\mathrm{pK}_{2}\right.\) of acetic acid is \(4.7\) ) (a) \(7.0\) (b) \(9.35\) (c) \(8.85\) (d) \(6.05\)

Match the following Column-I (a) Sodium acetate solution (b) Ferric chloride solution (c) Pure water (d) Ammonium acetate solution Column-II (p) \(\mathrm{pH}<7\) (q) \(\mathrm{pH}>7\) (r) salt hydrolysis (s) \(\mathrm{pH}=7\) (t) \(\mathrm{pH}>14\)

Match the following (a) HF (p) Strength of acid increases with concentration (b) \(\mathrm{CH}_{3} \mathrm{COOH}\) (q) Weak acid (c) \(\mathrm{H}_{3} \mathrm{BO}_{3}\) (r) Strength of acid increases with dilution (d) \(\mathrm{H}_{3} \mathrm{PO}_{2}\) (s) Acid shows hydrogen bonding (t) Monobasic acid.

Match the following (a) \(\mathrm{FeCl}_{3}\) solution (aqueous) (p) \(\mathrm{pH}<7\) (b) \(\mathrm{CH}_{3}\) COONa solution (aqueous) (q) \(\mathrm{pH}>7\) (c) Mixture of \(0.1 \mathrm{M}\) acetic acid and (r) \(\mathrm{pH}=7\) \(0.1 \mathrm{M}\) sodium acetate (aqueous) (d) \(0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONH}_{4}\) (aqueous) (s) acidic (t) basic

Assertion: When aqueous solution of \(\mathrm{CH}_{3} \mathrm{COONH}_{4}\) is diluted, then its degree of hydrolysis increases. Reason: Ammonium acetate is the salt of weak acid and weak base, its degree of hydrolysis does not depend on the concentration.

Assertion: Solubility of group II hydroxides increases down the group. Reason: Decrease in hydration energy is less than the decrease in lattice energy down the group.

Acetic acid solution was \(66.6 \%\) neutralized by adding a base. If \(\mathrm{pK}_{a}\) of acetic acid is \(4.7\), the \(\mathrm{pH}\) of the above solution is approximately

The sparingly soluble salt \(\mathrm{M}(\mathrm{OH})_{x}\) has \(\mathrm{K}_{\mathrm{se}}=4 \times 10^{-12}\). Its solubility is \(10^{-4} \mathrm{M}\). The value of \(\mathrm{x}\) is

A \(40 \mathrm{ml}\) sample of an aqueous solution of the methylamine at \(25^{\circ} \mathrm{C}\) is titrated with \(0.15 \mathrm{M} \mathrm{HCl}\) and the equivalence point is reached when \(40 \mathrm{ml}\) of the acid have been added. The \(\mathrm{pH}\) at the equivalence point is (Given: \(\mathrm{K}\), for \(\mathrm{CH}_{3} \mathrm{NH}_{3}^{+}\)is \(\left.4 / 3 \times 10^{-11}\right)\).

\(\mathrm{K}_{\mathrm{a}}\) for \(\mathrm{HCN}\) is \(5 \times 10^{-10}\) at \(25^{\circ} \mathrm{C}\). For maintaining a constant \(\mathrm{pH}\) of 9, the vol of \(5 \mathrm{M}\) KCN solution required to be added to \(10 \mathrm{ml}\) of \(2 \mathrm{M}\) HCN solution is

\(\mathrm{pH}\) of \(10^{-10} \mathrm{M} \mathrm{HCl}\) solution at \(25^{\circ} \mathrm{C}\) is approximately

A certain buffer solution contains equal conc. of \(\mathrm{X}^{-}\) and HX. The \(\mathrm{K}\) of \(\mathrm{HX}\) is \(10^{-7} .\) The \(\mathrm{pH}\) of the buffer solution is

If \(50 \mathrm{ml}\) of \(0.2 \mathrm{M} \mathrm{NaCN}\) is mixed with \(50 \mathrm{ml}\) of \(0.2\) M \(\mathrm{HCl}\), then \(\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]=\left[\mathrm{CN}^{-}\right]=\mathrm{x} \times 10^{-6}\) where \(\mathrm{x}\) is \(\left(\mathrm{K}_{b}\right.\) for \(\left.\overrightarrow{C N}^{-}=2 \times 10^{-5}\right)\)

\(10 \mathrm{~mL}\) of pure ethanol of density \(0.785 \mathrm{~g} / \mathrm{mL}\) was diluted with water to a final volume of \(100 \mathrm{~mL}\). The density of the resulting solution was \(0.9866 \mathrm{~g} / \mathrm{mL}\). The percentage by weight of ethanol is about

For the reaction \(\frac{\mathrm{dx}}{\mathrm{dt}}=\mathrm{k}\left[\mathrm{H}^{+}\right]^{\mathrm{n}} .\) If \(\mathrm{pH}\) of the reaction medium changes from two to one, rate becomes 100 times that of the value at \(\mathrm{pH}=2\). The order of reaction is

The solubility of \(\mathrm{AgCN}\) in a buffer solution is \(1.58\) \(\times 10^{-5}\) mol litre \(^{-1} .\) Given \(K_{\text {?p }}\) of \(\mathrm{AgCN}=1.2 \times 10^{-16}\) and \(\mathrm{K}_{\mathrm{a}}\) for \(\mathrm{HCN}\) is \(4.8 \times 10^{-10} .\) The \(\mathrm{pH}\) of the buffer is

Iron (II) sulphide is heated in air to form compound 'A', an oxide of sulphur. Compound 'A' is dissolved in water to give an acid. The basicity of this acid is

The \(\mathrm{K}_{\text {sp }}\) of \(\mathrm{Mg}(\mathrm{OH})_{2}\) is \(1 \times 10^{-12} .\) A \(0.01 \mathrm{M} \mathrm{MgCl}_{2}\) solution will precipitate at what limiting \(\mathrm{pH}\) value?

A buffer solution contains monobasic acid and its salt of concentration \(3 \mathrm{M}\) ad \(0.3 \mathrm{M}\) respectively. If \(\mathrm{pK}_{2}\) of acid is 5, the \(\mathrm{pH}\) of the solution is

\(1.75 \mathrm{gm}\) of solid \(\mathrm{NaOH}\) are added to \(250 \mathrm{ml}\) of \(0.1 \mathrm{M}\) \(\mathrm{NiCl}_{2}\) solution. Calculate the approximate \(\mathrm{pH}\) of final solution. \(\left(\mathrm{K}_{\text {s }}\right.\) of \(\mathrm{Ni}(\mathrm{OH})_{2}=1.6 \times 10^{-14}\) ).

A monoprotic acid in a \(0.1 \mathrm{M}\) solution ionizes to \(0.001 \%\). If its ionization constant is \(\frac{10^{-\mathrm{x}}}{100}\), the value of \(\mathrm{x}\) is

Find the \(\mathrm{pH}\) of a \(10^{-2} \mathrm{M}\) solution of sodium salt of substituted benzoic acid if the dissociation constant of substituted benzoic acid is \(1 \times 10^{-6}\) at \(298 \mathrm{~K}\)

Clothings washed in water that has a manganese concentration exceeding \(0.1 \mathrm{mg} \mathrm{L}^{-1}\left(1.8 \times 10^{-6} \mathrm{M}\right)\) may be stained by the manganese, but the amount of \(\mathrm{Mn}^{2+}\) in water can be reduced by adding base. If a laundry wishes to add a buffer to keep the \(\mathrm{pH}\) high enough to precipitate manganese as the hydroxide, \(\mathrm{Mn}(\mathrm{OH})_{2}\), with \(\mathrm{pH}\) required to keep \(\left[\mathrm{Mn}^{2+}\right]\) equal to \(1.8 \times 10^{-6} \mathrm{M}\) is \(2 \mathrm{x}\). Find \(\mathrm{x}\) (nearest integral value). \(\mathrm{K}_{\mathrm{sp}}\) of \(\mathrm{Mn}(\mathrm{OH})_{2}\) is \(4.5 \times 10^{-14}\).

\(\mathrm{pOH}\) of an aqueous solution is \(5.0 .\) If the conc. of \(\left[\mathrm{H}^{+}\right]\) in that solution is \(10^{-x} \mathrm{M}\), the value of \(\mathrm{x}\) is

Calculate the \(\mathrm{pH}\) of \(10^{-8} \mathrm{M} \mathrm{HCl} .(\log 11=1.0414)\)

If the solubility of \(\mathrm{RNH}_{2}(\mathrm{~g})\) in water at \(1 \mathrm{~atm}\) and \(273 \mathrm{~K}\) is \(22.4 \mathrm{~L}\) volumes of \(\mathrm{RNH}_{2}\) per unit volume of water. If \(\mathrm{pK}_{\mathrm{b}}\) of \(\mathrm{RNH}_{2}\) is 4 . Find the maximum \(\mathrm{pOH}\) that can be attained by dissolving \(\mathrm{RNH}_{2}\) in water.