Chapter 8

The \(\mathrm{pH}\) of a solution obtained by mixing equal volume of solutions having \(\mathrm{pH}=3\) and \(\mathrm{pH}=4\). [log \(5.5=\) \(0.7404]\) (a) \(3.26\) (b) \(3.5\) (c) \(4.0\) (d) \(3.42\)

Solid \(\mathrm{AgNO}_{3}\) is added slowly to a buffer solution of \(\mathrm{pH}\) \(=10\) to precipitate \(\mathrm{AgOH}\). The \(\left[\mathrm{Ag}^{+}\right]\)concentration in the solution is \(\left[\mathrm{K}_{s}(\mathrm{AgOH})=10^{-10}\right]\) (a) \(10^{-4} \mathrm{M}\) (b) \(10^{-5} \mathrm{M}\) (c) \(10^{-6} \mathrm{M}\) (d) \(10^{-7} \mathrm{M}\)

If \(\mathrm{pK}_{\mathrm{b}}\) for \(\mathrm{CN}-\) at \(25^{\circ} \mathrm{C}\) is \(4.7\), the \(\mathrm{pH}\) of \(0.5 \mathrm{M}\) aqueous NaCN solution is (a) 10 (b) \(11.5\) (c) 11 (d) 12

Which one of these is not an acid salt ? (a) \(\mathrm{NaH}_{2} \mathrm{PO}_{2}\) (b) \(\mathrm{NaH}_{2} \mathrm{PO}_{3}\) (c) \(\mathrm{Na}_{2} \mathrm{H}_{2} \mathrm{~S}_{2} \mathrm{O}_{7}\) (d) \(\mathrm{NaH}_{2} \mathrm{PO}_{4}\)

A buffer solution is prepared by mixing \(20 \mathrm{ml}\) of \(0.1 \mathrm{M}\) \(\mathrm{CH}_{3} \mathrm{COOH}\) and \(40 \mathrm{ml}\) of \(0.5 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONa}\) and then diluted by adding \(100 \mathrm{ml}\) of distilled water. The \(\mathrm{pH}\) of resulting buffer solution is (Given \(\mathrm{pKa} \mathrm{CH}_{3} \mathrm{COOH}=4.76\) ) (a) \(5.76\) (b) \(4.67\) (c) \(3.48\) (d) \(5.9\)

An acid-base indicator has \(\mathrm{K}_{\mathrm{a}}=3.0 \times 10^{-5} .\) The acid form of the indicator is red and the basic form is blue. The \(\left[\mathrm{H}^{+}\right]\)required to change the indicator from \(75 \%\) red to \(75 \%\) blue is (a) \(8 \times 10^{-5} \mathrm{M}\) (b) \(9 \times 10^{-5} \mathrm{M}\) (c) \(1 \times 10^{-5} \mathrm{M}\) (d) \(3 \times 10^{-4} \mathrm{M}\)

\(\mathrm{AgOH}\) is added to \(\mathrm{NaCl}\) solution to form \(\mathrm{AgCl}\) precipitate. After the precipitation, the \(\mathrm{pH}\) of the solution is 8 . The \(\left[\mathrm{Cl}^{-}\right]\)is \(\left(\mathrm{K}_{\mathrm{sp}}\right.\) of \(\mathrm{AgCl}=10^{-12}, \mathrm{~K}_{\text {op }}\) of \(\left.\mathrm{AgOH}=10^{-10}\right)\) (a) \(10^{-6} \mathrm{M}\) (b) \(10^{-4} \mathrm{M}\) (c) \(10^{-8} \mathrm{M}\) (d) \(10^{-10} \mathrm{M}\)

For the reaction \(\left[\mathrm{Ag}(\mathrm{CN})_{2}\right](\mathrm{aq}) \rightleftharpoons \mathrm{Ag}^{+}(\mathrm{aq})+2 \mathrm{CN}^{-}\) (aq), the equilibrium constant at \(25^{\circ} \mathrm{C}\) is \(4.0 \times 10^{-19}\). Calculate the silver ion concentration in a solution which was originally \(0.10 \mathrm{M}\) in \(\mathrm{KCN}\) and \(0.03 \mathrm{M}\) in \(\mathrm{AgNO}_{3}\). (a) \(2.5 \times 10^{-18} \mathrm{M}\) (b) \(1.5 \times 10^{-18} \mathrm{M}\) (c) \(5.5 \times 10^{-18} \mathrm{M}\) (d) \(7.5 \times 10^{-18} \mathrm{M}\)

Separate solutions of four sodium salts \(\mathrm{NaW}, \mathrm{NaX}\), \(\mathrm{NaY}\) and \(\mathrm{NaZ}\) had \(\mathrm{pH} 7.0,9.0,10.0\) and \(11.0 \mathrm{respec}-\) tively. When each solution is \(0.1 \mathrm{M}\), the strongest acid is (a) HW (b) \(\mathrm{HX}\) (c) HY (d) \(\mathrm{HZ}\)

\(0.1 \mathrm{M}\) 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? \(\left(\mathrm{K}_{\text {sp }}\right.\) of \(\mathrm{AgCl}=10^{-12}\) ) (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 \(\left.\mathrm{K}_{w}=1.0 \times 10^{-14}\right]\) is (a) \(8.2\) (b) \(9.6\) (c) \(5.26\) (d) \(2.48\)

Hydrolysis constant \(K_{A}\) and \(K_{B}\) 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 \(10^{-6}\) 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) \(\mathrm{Cd}(\mathrm{OH})_{2}\left(\mathrm{~K}_{\text {? }}=8 \times 10^{-6}\right)\) (c) \(\mathrm{Mg}(\mathrm{OH})_{2}\left(\mathrm{~K}_{\mathrm{sp}}=3 \times 10^{-11}\right)\) (d) \(\mathrm{Fe}(\mathrm{OH})_{3}\left(\mathrm{~K}_{\mathrm{sp}}=8 \times 10^{-16}\right)\)

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 \(0.2 \mathrm{M} \mathrm{NaOH}\left[\mathrm{K}_{5}\right.\) 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) \(\mathrm{K}_{\mathrm{sp}}(\mathrm{ZnS})<\mathrm{K}_{\text {?p }}(\mathrm{PbS})\) (b) \(\mathrm{K}_{\mathrm{s}}(\mathrm{ZnS})>\mathrm{K}_{\mathrm{s}}(\mathrm{PbS})\) (c) \(\mathrm{H}_{2} \mathrm{~S}\) decreases the \(\mathrm{K}_{\text {sp }}\) of \(\mathrm{ZnS}\) (d) \(\mathrm{H}_{2} \mathrm{~S}\) increases the \(\mathrm{K}_{\text {sp }}\) of \(\mathrm{PbS}\)

When equal volumes of the following solutions are mixed, the precipitation of \(\mathrm{AgCl}\left(\mathrm{K}_{\mathrm{sp}}=1.8 \times 10^{-10}\right)\) 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) \(\mathrm{K}_{w}\) of boiling water is greater than \(10^{-14}\). (c) Ionic product of water at \(25^{\circ} \mathrm{C}\) is \(10^{-14}\) (d) \(\mathrm{pH}+\mathrm{pOH}=\mathrm{pK}_{\mathrm{w}^{-}}\)

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

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 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) \(0.5 \mathrm{M} \mathrm{H}_{2} \mathrm{CO}_{3}+0.5 \mathrm{M} \mathrm{NaHCO}_{3}\)

For the reaction \(\mathrm{AB}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{A}(\mathrm{g})+\mathrm{B}_{2}(\mathrm{~g})\) The degree of dissociation ' \(\alpha\) ' is negligible as compared to 1 (unity); the degree of dissociation may be expressed as: (a) \(\alpha \propto \frac{1}{\sqrt{\mathrm{P}}}\) (b) \(\alpha \propto \sqrt{\mathrm{V}}\) (c) \(\alpha \propto \frac{1}{\mathrm{P}}\) (d) \(\alpha \propto \frac{1}{\mathrm{~V}}\)

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) \(0.5 \mathrm{~mol}\) of pyridine \(+0.5 \mathrm{~mol}\) of Pyridinium chloride (b) \(0 . \mathrm{I} \mathrm{mol}\) of \(\mathrm{NaOH}+0.15 \mathrm{~mol}\) of \(\mathrm{CH}_{3} \mathrm{COOH}\) (c) \(\mathrm{CH}_{3} \mathrm{COONH}_{4}\) (d) \(0.25\) mol of \(\mathrm{NH}_{4} \mathrm{Cl}+0.5 \mathrm{~mol}\) of \(\mathrm{NaOH}\).

The concentration of acetic acid, which can be added to \(\mathrm{N} / 2\) formic acid so that the percentage dissociation of both acids is unchanged, would be \(\left(\mathrm{K}_{\mathrm{a}}\right.\) of \(\mathrm{HCO}_{2} \mathrm{H}\) and \(\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}\) are \(2.4 \times 10^{-4} \mathrm{M}\) and \(1.8 \times 10^{-5} \mathrm{M}\) respectively) (a) \(20 \mathrm{~N} / 2\) (b) \(\mathrm{N} / 2\) (c) N/4 (d) \(10 \mathrm{~N} / 3\)

Equal volumes of \(\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}\) (c \(\mathrm{M}\) ) 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 \(\mathrm{HCl}\) 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 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 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) \(\mathrm{MB}>\mathrm{MB}_{3}>\mathrm{M}_{2} \mathrm{~B}\)

\(50 \mathrm{~mL}\) of \(0.1 \mathrm{M}\) aqueous acetic acid is titrated with \(10 \mathrm{~mL}\) of \(0.1 \mathrm{M}\) aqueous \(\mathrm{NaOH}\) solution. The \(\mathrm{pH}\) of resulting solution is \(\left(\mathrm{pK}_{2}\right.\) of acetic acid is \(4.7, \log 2=\) \(0.3010)\) (a) \(5.098\) (b) \(5.030\) (c) \(4.098\) (d) \(5.3020\)

\(50 \mathrm{~mL}\) 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 \(\mathrm{KOH}\) 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 Column-I (a) HF (b) \(\mathrm{CH}_{3} \mathrm{COOH}\) ( \(\mathrm{COOH}\) (c) \(\mathrm{H}_{3} \mathrm{BO}_{3}\) (d) \(\mathrm{H}_{3} \mathrm{PO}_{2}\) Column-II (p) Strength of acid increases with concentration (q) Weak acid (r) Strength of acid increases with dilution (s) Acid shows hydrogen bonding (t) Monobasic acid.

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

In the following questions two statements (Assertion) (A) and Reason (R) are given. Mark (a) If both \(\mathrm{A}\) and \(\mathrm{R}\) are correct and \(\mathrm{R}\) is the correct explanation of \(\mathrm{A}\). (b) If both \(\mathrm{A}\) and \(\mathrm{R}\) are correct but \(\mathrm{R}\) is not the correct expalnation of \(\mathrm{A}\). (c) \(\mathrm{A}\) is true but \(\mathrm{R}\) is false. (d) A is false but \(R\) is true. (e) \(\mathrm{A}\) and \(\mathrm{R}\) both are false. 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.

\(\mathrm{K}_{\mathrm{a}} \times \mathrm{K}_{\mathrm{a}}\) for \(\mathrm{H}_{2} \mathrm{~S}=1.0 \times 10^{-21} \mathrm{M}^{2} .\) The concentration of \(\left[\mathrm{S}^{2-}\right]\) ion present in \(1 \mathrm{~L}\) of \(0.1 \mathrm{M} \mathrm{H}_{2} \mathrm{~S}\) having \(\left[\mathrm{H}^{+}\right]\) equal to \(0.1 \mathrm{M}\) is \(\mathrm{x} \times 10^{-20}\). The value of \(\mathrm{x}\) is

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

If the \(\left[\mathrm{H}^{+}\right]\)is increased by 10 times, its \(\mathrm{pH}\) will change by ______ units.

\(\mathrm{K}\), 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

The dissociation constants of \(\mathrm{CH}_{3} \mathrm{COOH}\) and \(\mathrm{NH}_{4} \mathrm{OH}\) in aqueous solution are almost the same. The \(\mathrm{pH}\) of a solution of \(0.01 \mathrm{~N} \mathrm{CH}_{3} \mathrm{COOH}\) is \(4.0\) at \(25^{\circ} \mathrm{C}\). The \(\mathrm{pOH}\) of \(0.01 \mathrm{~N} \mathrm{NH}_{4} \mathrm{OH}\) solutions at the same temperature will be

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

\(10 \mathrm{~mL}\) 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 \(\frac{d x}{d t}=k\left[H^{+}\right]^{n}\). 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 \(\mathrm{K}_{s}\) 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 \(' A^{\prime}\), 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 \(\mathrm{pK}_{\mathrm{a}}\) of acid is 5 , the \(\mathrm{pH}\) of the solution is