Chapter 8

pKa values of three acids \(\mathrm{A}, \mathrm{B}\) and \(\mathrm{C}\) are \(4.3,3.3\) and 5.5 respectively. Which of the following represents the correct order of acid strength? (a) \(\mathrm{A}>\mathrm{B}>\mathrm{C}\) (b) \(C>A>B\) (c) \(\mathrm{B}>\mathrm{A}>\mathrm{C}\) (d) \(\mathrm{C}>\mathrm{B}>\mathrm{A}\)

Which of the following on reaction with \(\mathrm{H}_{2} \mathrm{~S}\) does not produce metallic sulphide? (a) \(\mathrm{CdCl}_{2}\) (b) \(\mathrm{ZnCl}_{2}\) (c) \(\mathrm{CoCl}_{2}\) (d) \(\mathrm{CuCl}_{2}\)

Which of the following statement is correct? 1\. The \(\mathrm{pH}\) of \(1.0 \times 10^{-8} \mathrm{M}\) solution of \(\mathrm{HCl}\) is 8 2\. The conjugate base of \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)is \(\mathrm{HPO}_{4}^{2-}\) 3\. Autoprotolysis constant of water increases with temperature 4\. When a solution of a weak monoprotic acid is titrated against a strong base at half neutralization point, \(\mathrm{pH}=(1 / 2) \mathrm{pKa}\). (a) 2,3 (b) \(1,2,3\) (c) 3,4 (d) \(2,3,4\)

The solubility of \(\mathrm{A}_{2} \mathrm{X}_{3}\) is \(\mathrm{y} \mathrm{mol} \mathrm{dm}^{-3} .\) Its solubility product is (a) \(6 \mathrm{y}^{4}\) (b) \(64 \mathrm{y}^{4}\) (c) \(36 \mathrm{y}^{5}\) (d) \(108 \mathrm{y}^{5}\)

If pKb for fluoride ion at \(25^{\circ} \mathrm{C}\) is \(10.83\), the ionization constant of hydrofluoric acid at this temperature is (a) \(1.74 \times 10^{-5}\) (b) \(3.52 \times 10^{-3}\) (c) \(6.75 \times 10^{-4}\) (d) \(5.38 \times 10^{-2}\)

The pKa pf HCN is \(9.30\). The pH of a solution prepared by mixing \(2.5\) moles of \(\mathrm{KCN}\) and \(2.5\) moles of \(\mathrm{HCN}\) in water and making up the total volume to \(500 \mathrm{ml}\) is (a) \(9.30\) (b) \(8.30\) (c) \(7.30\) (d) \(10.30\)

What is the decreasing order of strength of the bases? \(\mathrm{OH}^{-}, \mathrm{NH}_{2}^{-}, \mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}\)and \(\mathrm{CH}_{3}-\mathrm{CH}_{2}^{-2}\) (a) \(\mathrm{CH}_{3}-\mathrm{CH}_{2}^{-},>\mathrm{NH}_{2}^{-}>\mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}>\mathrm{OH}^{-}\) (b) \(\mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}>\mathrm{CH}_{3}-\mathrm{CH}_{2}^{-}>\mathrm{NH}_{2}->\mathrm{OH}^{-}\) (c) \(\mathrm{OH}^{-}>\mathrm{NH}_{2}^{-}>\mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}>\mathrm{CH}_{3}-\mathrm{CH}_{2}\) (d) \(\mathrm{NH}_{3}^{-}>\mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}>\mathrm{OH}^{-}>\mathrm{CH}_{2}-\mathrm{CH}_{3}^{-}\)

The following equilibrium is established when hydrogen chloride is dissolved in acetic acid. \(\mathrm{HCl}+\mathrm{CH}_{3} \mathrm{COOH} \leftrightarrow \mathrm{Cl}^{-}+\mathrm{CH}_{3} \mathrm{COOH}_{2}^{+}\) The set that characterizes the conjugate acid base pair is (a) \(\left(\mathrm{HCl}, \mathrm{CH}_{3} \mathrm{COOH}\right)\) and \(\left(\mathrm{CH}_{3} \mathrm{COOH}_{2}^{+}, \mathrm{Cl}^{-}\right)\) (b) \(\left(\mathrm{HCl}, \mathrm{CH}_{3} \mathrm{COOH}_{2}^{+}\right)\)and \(\left(\mathrm{HCl}, \mathrm{CH}_{3} \mathrm{COOH}_{2}^{+}\right)\)and \(\left(\mathrm{CH}_{3} \mathrm{COOH}, \mathrm{Cl}^{-}\right)\) (c) \(\left(\mathrm{CH}_{3} \mathrm{COOH}_{2}^{+}, \mathrm{HCl}\right)\) and \(\left(\mathrm{Cl}^{-}, \mathrm{CH}_{3} \mathrm{COOH}\right)\) (d) \(\left(\mathrm{HCl}, \mathrm{Cl}^{-}\right)\)and \(\left(\mathrm{CH}_{3} \mathrm{COOH}_{2}^{+}, \mathrm{CH}_{3} \mathrm{COOH}\right)\)

The pKa of acetyl salicylic acid (aspirin) is \(3.5 .\) The \(\mathrm{pH}\) of gastric juice in human stomach is about \(2-3\) and \(\mathrm{pH}\) in the small intestine is about 8. Aspirin will be (a) ionized in the small intestine and almost unionized in the stomach (b) unionized in the small intestine and in the stomach (c) completely ionized in the small intestine and in the stomach (d) ionized in the stomach and almost unionized in the small intestine.

An example of a reversible reaction is (a) \(\mathrm{KNO}_{3}(\mathrm{aq})+\mathrm{NaCl}(\mathrm{aq})=\mathrm{KCl}(\mathrm{aq})+\mathrm{NaNO}_{3}(\mathrm{aq})\) (b) \(2 \mathrm{Na}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})=2 \mathrm{NaOH}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g})\) (c) \(\mathrm{AgNO}_{3}(\mathrm{aq})+\mathrm{HCl}(\mathrm{aq})=\mathrm{AgCl}(\mathrm{s})+\mathrm{NaNO}_{3}\) (aq) (d) \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+2 \mathrm{NaI}(\mathrm{aq})=\mathrm{PbI}_{2}(\mathrm{~s})+2 \mathrm{NaNO}_{3}\) (aq)

The precipitate of \(\mathrm{CaF}_{2}\left(\mathrm{Ksp}=1.7 \times 10^{-10}\right)\) is obtained when equal volumes of the following are mixed (a) \(10^{-2} \mathrm{M} \mathrm{Ca}^{2+}+10^{-3} \mathrm{MF}^{-}\) (b) \(10^{-3} \mathrm{M} \mathrm{Ca}^{2+}+10^{-5} \mathrm{MF}^{-}\) (c) \(10^{-4} \mathrm{M} \mathrm{Ca}^{2+}+10^{-4} \mathrm{MF}^{-}\) (d) \(10^{-5} \mathrm{M} \mathrm{Ca}^{2+}+10^{-3} \mathrm{MF}^{-}\)

The oxidation of \(\mathrm{SO}_{2}\) by \(\mathrm{O}_{2}\) to \(\mathrm{SO}_{3}\) is an exothermic reaction. They yield of \(\mathrm{SO}_{3}\) will be maximum if (a) temperature is reduced and pressure is increased (b) temperature is increased and pressure is kept constant (c) both temperature and pressure are reduced (d) both temperature and pressure are increased

Solution of \(0.1 \mathrm{~N} \mathrm{NH}_{4} \mathrm{OH}\) and \(0.1 \mathrm{~N} \mathrm{NH}_{4} \mathrm{Cl}\) has \(\mathrm{pH}\) \(9.25\), then find out \(\mathrm{pKb}\) of \(\mathrm{NH}_{4} \mathrm{OH}\) (a) \(9.25\) (b) \(4.75\) (c) \(3.75\) (d) \(8.25\)

Which has highest \(\mathrm{pH}\) ? (a) \(\mathrm{CH}_{3} \mathrm{COOK}\) (b) \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) (c) \(\mathrm{NH}_{4} \mathrm{Cl}\) (d) \(\mathrm{NaNO}_{3}\)

The rapid change of \(\mathrm{pH}\) near the stoichiometric point of an acid- base titration is the basis of indicator detection. \(\mathrm{pH}\) of the solution is related to the concentrations of the conjugate acid (HIn) and base (In \(^{-}\)) forms of the indicator by the expression (a) \(\log \left[\frac{\operatorname{In}^{-}}{\mathrm{HIn}}\right]=\mathrm{pK}_{\mathrm{ln}}-\mathrm{pH}\) (b) \(\log \left[\frac{\mathrm{HIn}}{\mathrm{In}^{-}}\right]=\mathrm{pK}_{\mathrm{ln}}+\mathrm{pH}\) (c) \(\log \left[\frac{\mathrm{HIn}}{\mathrm{In}}\right]=\mathrm{pH}_{-} \mathrm{pK}_{\mathrm{ln}}\) (d) \(\log \left[\frac{\operatorname{In}}{\mathrm{HIn}}\right]=\mathrm{pH}_{-} \mathrm{pK}_{\mathrm{ln}}\)

The hydrogen ion concentration of a \(10^{-8} \mathrm{M} \mathrm{HCl}\) aqueous solution at \(298 \mathrm{~K}\left(\mathrm{Kw}=10^{-14}\right)\) is (a) \(9.525 \times 10^{-8} \mathrm{M}\) (b) \(1.0 \times 10^{-8} \mathrm{M}\) (c) \(1.0 \times 10^{-6} \mathrm{M}\) (d) \(1.0525 \times 10^{-7} \mathrm{M}\)

Solubility of a \(\mathrm{M}_{2} \mathrm{~S}\) salt is \(3.5 \times 10^{-6}\) then find out solubility product. (a) \(1.7 \times 10^{-6}\) (b) \(1.7 \times 10^{-16}\) (c) \(1.7 \times 10^{-18}\) (d) \(1.7 \times 10^{-12}\)

Solubility of \(\mathrm{MX}_{2}\) type electrolyte is \(0.5 \times 10^{-4} \mathrm{~mol}\) \(\mathrm{L}^{-1}\). Then find out Ksp of electrolytes. (a) \(5 \times 10^{-12}\) (b) \(25 \times 10^{-10}\) (c) \(1 \times 10^{-13}\) (d) \(5 \times 10^{-13}\)

pKa value of four acids are given below. The strongest acid is (I) \(4.0\) (II) \(3.5\) (III) \(2.5\) (IV) 2 (a) I (b) II (c) III (d) IV

A solution has hydrogen ion concentration \(0.0005 \mathrm{M}\), its \(\mathrm{pOH}\) is (a) \(8.2798\) (b) \(10.6990\) (c) \(12.7854\) (d) \(13.3344\)

At \(25^{\circ} \mathrm{C}\) the \(\mathrm{pH}\) of solution containing \(0.10 \mathrm{M}\) sodium acetate and \(0.03 \mathrm{M}\) acetic acid is [pKa value of \(\left.\mathrm{CH}_{3} \mathrm{COOH}=4.57\right]\) (a) \(3.24\) (b) \(4.59\) (c) \(5.09\) (d) \(6.67\)

At \(80^{\circ} \mathrm{C}\), distilled water \(\left(\mathrm{H}_{3} \mathrm{O}^{+}\right)\)concentration is equal to \(1 \times 10^{-6} \mathrm{~mol} /\) litre. At the same temperature the value of \(\mathrm{Kw}\) is (a) \(1 \times 10^{-3}\) (b) \(1 \times 10^{-6}\) (c) \(1 \times 10^{-9}\) (d) \(1 \times 10^{-12}\)

When \(10 \mathrm{~mL}\) of \(0.1 \mathrm{M}\) acetic acid \((\mathrm{pKa}=5.0)\) is titrated against \(10 \mathrm{~mL}\) of \(0.1 \mathrm{M}\) ammonia solution \((\mathrm{pKb}=5.0\) ) the equivalence point occurs at \(\mathrm{pH}\) (a) \(5.0\) (b) \(6.0\) (c) \(9.0\) (d) \(7.0\)

The solubility of \(\mathrm{AgCl}\) in \(0.2 \mathrm{M} \mathrm{NaCl}\) is \([\mathrm{Ksp} \mathrm{AgCl}=\) \(\left.1.8 \times 10^{-10}\right]\) (a) \(1.8 \times 10^{-11} \mathrm{M}\) (b) \(9 \times 10^{-10} \mathrm{M}\) (c) \(6.5 \times 10^{-12} \mathrm{M}\) (d) \(5.6 \times 10^{-11} \mathrm{M}\)

Ionization constant of acetic acid is \(1.8 \times 10^{-5}\). The concentration of \(\mathrm{H}^{+}\)ions in \(0.1 \mathrm{M}\) solution is (a) \(1.8 \times 10^{-3} \mathrm{M}\) (b) \(1.8 \times 10^{-5} \mathrm{M}\) (c) \(1.3 \times 10^{-3} \mathrm{M}\) (d) \(1.34 \times 10^{-3} \mathrm{M}\)

The dissociation constant of a weak acid is \(4.9 \times 10^{-8}\), its percentage ionization at \(0.1 \mathrm{M}\) is (a) \(0.07 \%\) (b) \(0.007 \%\) (c) \(0.7 \%\) (d) \(0.0007 \%\)

The pKa of a weak acid is \(4.8\). What should be the ratio of \([\) acid \(] /[\mathrm{salt}]\), if a buffer of \(\mathrm{pH}=5.8\) is required? (a) \(0.1\) (b) 10 (c) 1 (d) 2

The \(\mathrm{pH}\) of a \(0.1 \mathrm{M}\) aqueous solution of a weak acid (HA) is 3 . What is its degree of dissociation? (a) \(1 \%\) (b) \(10 \%\) (c) \(50 \%\) (d) \(25 \%\)

The \(\mathrm{pH}\) range if methyl red indicator is (a) \(4.2\) to \(6.3\) (b) \(8.3\) to \(10.0\) (c) \(8.0\) to \(9.6\) (d) \(6.8\) to \(8.4\)

\(75 \mathrm{ml}\) of \(0.2 \mathrm{M} \mathrm{HCl}\) is mixed with \(25 \mathrm{ml}\) of \(\mathrm{M} \mathrm{HCl}\). To this solution, \(300 \mathrm{ml}\) of distilled water is added. What is the \(\mathrm{pH}\) of the resultant solution? (a) 1 (b) 2 (c) 4 (d) \(0.2\)

The dissociation constant of two acids \(\mathrm{HA}_{1}\) and \(\mathrm{HA}_{2}\) are \(3.0 \times 10^{-4}\) and \(1.8 \times 10^{-5}\) respectively. The relative strengths of the acids is (a) \(1: 16\) (b) \(1: 4\) (c) \(4: 1\) (d) \(16: 1\)

\(0.005 \mathrm{M}\) acid solution has \(5 \mathrm{pH}\). The percentage ionization of acid is (a) \(0.8 \%\) (b) \(0.6 \%\) (c) \(0.4 \%\) (d) \(0.2 \%\)

\(100 \mathrm{ml}\) of \(0.015 \mathrm{M}\) HCl solution is mixed with 100 \(\mathrm{ml}\) of \(0.005 \mathrm{M} \mathrm{HCl}\). What is the \(\mathrm{pH}\) of the resultant solution? (a) \(2.5\) (b) \(1.5\) (c) 2 (d) 1

The solubility product of \(\mathrm{A}_{2} \mathrm{X}_{3}\) is \(1.08 \times 10^{-23}\). Its solubility will be (a) \(1.0 \times 10^{-3} \mathrm{M}\) (b) \(1.0 \times 10^{-4} \mathrm{M}\) (c) \(1.0 \times 10^{-5} \mathrm{M}\)

\(\mathrm{M}(\mathrm{OH}) \mathrm{x}\) has \(\mathrm{Ksp}=4 \times 10^{-12}\) and solubility \(10^{-4} \mathrm{M}, \mathrm{x}\) is (a) 1 (b) 2 (c) 3 (d) 4

The \(\mathrm{pH}\) values of \(1 \mathrm{M}\) solutions of \(\mathrm{CH}_{3} \mathrm{COOH}\) (I), \(\mathrm{CH}_{3}, \mathrm{COONa}(\mathrm{II}), \mathrm{CH}_{3} \mathrm{COONH}_{4}(\mathrm{III})\), and \(\mathrm{KOH}\) (IV) will be in the order (a) IV \(>I I I>I I>I\) (b) IV \(>\mathrm{II}>\mathrm{III}>\mathrm{I}\) (c) \(\mathrm{I}>\mathrm{III}>\mathrm{II}>\mathrm{IV}\) (d) \(\mathrm{II}>\mathrm{I}>\mathrm{III}>\mathrm{IV}\)

For preparing a buffer solution of \(\mathrm{pH} 6\) by mixing sodium acetate and acetic acid, the ratio of the concentration of salt and acid should be \(\left(\mathrm{Ka}=10^{-5}\right)\) (a) \(1: 10\) (b) \(10: 1\) (c) \(100: 1\) (d) \(1: 100\)

The strongest Bronsted base among the following ions is (a) \(\mathrm{CH}_{3} \mathrm{O}^{-}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}\) (c) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHO}^{-}\) (d) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CO}^{-}\)

The decreasing order of acidic nature of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (I), \(\mathrm{H}_{3} \mathrm{PO}_{4}(\mathrm{II})\), and \(\mathrm{HClO}_{4}(\mathrm{III})\) is (a) \(\mathrm{I}>\mathrm{II}>\mathrm{III}\) (b) \(\mathrm{I}>\mathrm{III}>\mathrm{II}\) (c) \(\mathrm{III}>\mathrm{I}>\mathrm{II}\) (d) \(\mathrm{III}>\mathrm{II}>\mathrm{I}\)

The decreasing order of acidic nature of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (I), \(\mathrm{H}_{3} \mathrm{PO}_{4}(\mathrm{II})\), and \(\mathrm{HClO}_{4}(\mathrm{III})\) is (a) \(\mathrm{I}>\mathrm{II}>\mathrm{III}\) (b) \(\mathrm{I}>\mathrm{III}>\mathrm{II}\) (c) \(\mathrm{III}>\mathrm{I}>\mathrm{II}\) (d) \(\mathrm{III}>\mathrm{II}>\mathrm{I}\)

The Ka value of formic acid and acetic acid are respectively \(1.77 \times 10^{-4}\) and \(1.75 \times 10^{-5}\). the ratio of the acid strength of \(0.1 \mathrm{~N}\) acids is (a) \(0.1\) (b) \(0.3\) (c) \(3.178\) (d) 100

A weak monobasic acid is half neutralized by a strong base. If the \(\mathrm{pH}\) of the solution is \(5.4\), its \(\mathrm{pKa}\) is (a) \(6.8\) (b) \(2.7\) (c) \(5.4\) (d) \(10.8\)

The solubility of \(\mathrm{AgCl}\) in moles per litre when its solubility product is \(1.56 \times 10^{-10}\) at \(25^{\circ} \mathrm{C}\) is (a) \(0.576 \times 10^{-8} \mathrm{~mol} /\) litre (b) \(1.056 \times 10^{-4} \mathrm{~mol} /\) litre (c) \(1.249 \times 10^{-5} \mathrm{~mol} /\) litre (d) \(1.478 \times 10^{-6} \mathrm{~mol} /\) litre

If the solubility of sodium hexafluoroaluminate is 'a' mol/litre, its solubility product is (a) \(a^{8}\) (b) \(27 \mathrm{a}^{4}\) (c) \(180 \mathrm{a}^{3}\) (d) \(2916 \mathrm{a}^{8}\)

The solubility product of calcium fluoride is \(3.2 \times\) \(10^{-11} \mathrm{M}^{3}\). Its solubility in saturated solution is (a) \(8 \times 10^{-12} \mathrm{M}\) (b) \(2 \times 10^{-4} \mathrm{M}\) (c) \(4 \times 10^{-12} \mathrm{M}\) (d) \(1 \times 10^{-4} \mathrm{M}\)

Equal volumes of the following \(\mathrm{Ca}^{2+}\) and \(\mathrm{F}^{-}\)solutions are mixed. In which of the solutions will precipitation occurs? \(\left[\mathrm{Ksp}\right.\) of \(\left.\mathrm{CaF}_{2}=1.7 \times 10^{-10}\right]\) 1\. \(10^{-2} \mathrm{M} \mathrm{Ca}^{2+}+10^{-5} \mathrm{M} \mathrm{F}^{-}\) 2\. \(10^{-3} \mathrm{M} \mathrm{Ca}^{2+}+10^{-3} \mathrm{M} \mathrm{F}^{-}\) 3\. \(10^{-4} \mathrm{M} \mathrm{Ca}^{2+}+10^{-2} \mathrm{M} \mathrm{F}^{-}\) 4\. \(10^{-2} \mathrm{M} \mathrm{Ca}^{2+}+10^{-3} \mathrm{M} \mathrm{F}^{-}\) Select the correct answer using the codes given below: (a) in 4 only (b) in 1 and 2 (c) in 3 and 4 (d) in 2,3 and 4

\(\mathrm{ZnS}\) is not precipitated by passing \(\mathrm{H}_{2} \mathrm{~S}\) in acidic medium but \(\mathrm{CuS}\) is precipitated. The reason for it is (a) \(\mathrm{Ksp} \mathrm{CuS}<<\mathrm{Ksp} \mathrm{ZnS}\) (b) \(\mathrm{Ksp} \mathrm{CuS}>>\mathrm{Ksp} \mathrm{ZnS}\) (c) \(\mathrm{Ksp} \mathrm{CuS}=\mathrm{Ksp} \mathrm{ZnS}\) (d) none of these

The hydrogen ion concentration is \(0.2 \mathrm{M}\) ethanoic acid \(\left(\mathrm{K}_{\mathrm{C}}=2 \times 10^{-5} \mathrm{~mol} \mathrm{dm}^{-3}\right)\) is approximately (a) \(10^{-4}\) (b) \(2 \times 10^{-2}\) (c) \(2 \times 10^{-6}\) (d) \(2 \times 10^{-3}\)

The \(\mathrm{pH}\) of solution made by mixing \(50 \mathrm{~mL}\) of \(0.01 \mathrm{M}\) barium hydroxide solution with \(50 \mathrm{~mL}\) of \(\mathrm{H}_{2} \mathrm{O}\) is (a) \(3.0\) (b) \(6.0\) (c) \(12.0\) (d) \(15.0\)

Find the molar solubility of \(\mathrm{Fe}(\mathrm{OH})_{3}\) in a buffer solution that \(0.10 \mathrm{M}\) in \(\mathrm{NH}_{4} \mathrm{Cl}\) and \(0.10 \mathrm{M}\) in \(\mathrm{NH}_{3}\). If \(\mathrm{K}_{\mathrm{b}}\) \(\left(\mathrm{NH}_{3}\right)=1.8 \times 10^{-5}\) and \(\mathrm{Ksp}\left[\mathrm{Fe}(\mathrm{OH})_{3}\right]=2.6 \times 10^{-39}\) (a) \(4.458 \times 10^{-25} \mathrm{M}\) (b) \(3.458 \times 10^{-25} \mathrm{M}\) (c) \(2.229 \times 10^{-24} \mathrm{M}\) (d) \(4.458 \times 10^{-22} \mathrm{M}\)