Chapter 8

The acid ionization (hydrolysis) constant of \(\mathrm{Zn}^{2+}\) is \(1.0\) \(\times 10^{-9} .\) Which of the following statements are correct? (i) the basic dissociation constant of \(\mathrm{Zn}(\mathrm{OH})^{+}\)is \(1.0 \times 10^{5}\) (ii) the \(\mathrm{pH}\) of \(0.001 \mathrm{M} \mathrm{ZnCl}_{2}\) solution is 6 (iii) the basic dissociation constant of \(\mathrm{Zn}(\mathrm{OH})^{+}\)is \(1.0 \times 10^{-5}\) (iv) the \(\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]\)ion concentration in \(0.001 \mathrm{M} \mathrm{ZnCl}_{2}\) solution is \(1.0 \times 10^{-4}\). (a) 1,2 (b) 2,3 (c) 3,4 (d) \(1,2,4\)

A \((\mathrm{OH})_{2}\) is a partially soluble substance. Its \(\mathrm{Ksp}\) value is \(4 \times 10^{-12}\), which of the following statement is correct? (1) The solubility is unaffected by \(\mathrm{pH}\) of the medium (2) Its solubility has been decreased in a buffered medium at \(\mathrm{pH}\) at \(1 \mathrm{~L}\) (3) Its solubility has been increased in a buffered medium having \(\mathrm{pH}\) at 9 (4) Its saturated solution has \(\mathrm{pH}\) is equal to \(10.3\) (a) \(1,2,3\) (b) 3 and 4 (c) 2 and 3 (d) 2,3 and 4

A base dissolved in water yields a solution with a hydroxyl ion concentration of \(0.05\) mol litre \(^{-1}\). The solution is (a) basic (b) acid (c) neutral (d) either (b) or (c)

Ionization constant of \(\mathrm{CH}_{3} \mathrm{COOH}\) is \(1.7 \times 10^{-5}\) and concentration of \(\mathrm{H}^{+}\)ion is \(3.4 \times 10^{-4}\). Then initial concentration of \(\mathrm{CH}_{3} \mathrm{COOH}\) is (a) \(3.4 \times 10^{-4}\) (b) \(3.4 \times 10^{-3}\) (c) \(6.8 \times 10^{-4}\) (d) \(6.8 \times 10^{-3}\)

At \(25^{\circ} \mathrm{C}\) the dissociation constant of a base, \(\mathrm{BOH}\) is \(1.0 \times 10^{-12}\), the concentration of hydroxyl ions \(0.01 \mathrm{M}\) aqueous solution of the base would become (a) \(2.0 \times 10^{-6} \mathrm{~mol} \mathrm{~L}^{-1}\) (b) \(1.0 \times 10^{-5} \mathrm{~mol} \mathrm{~L}^{-1}\) (c) \(1.0 \times 10^{-6} \mathrm{~mol} \mathrm{~L}^{-1}\) (d) \(1.0 \times 10^{-7} \mathrm{~mol} \mathrm{~L}^{-1}\)

The solubility product of \(\mathrm{AgI}\) at \(25^{\circ} \mathrm{C}\) is \(1.0 \times 10^{-16}\) \(\mathrm{mol}^{2} \mathrm{~L}^{-2}\). The solubility of AgI in \(10^{-4} \mathrm{~N}\) solution of \(\mathrm{KI}\) at \(25^{\circ} \mathrm{C}\) is (in \(\mathrm{mol} \mathrm{L}^{-1}\) ) (a) \(1.0 \times 10^{-10}\) (b) \(1.0 \times 10^{-8}\) (c) \(1.0 \times 10^{-16}\) (d) \(1.0 \times 10^{-12}\)

One litre of \(0.5 \mathrm{M}\) KCI solution is electrolysed for one minute in a current of \(16.08 \mathrm{~mA}\). Considering \(100 \%\) efficiency, the \(\mathrm{pH}\) of resulting solution will be (a) 7 (b) 9 (c) 8 (d) 10

\(\mathrm{Ag}^{+}+\mathrm{NH}_{3} \rightleftharpoons\left[\mathrm{Ag}\left(\mathrm{NH}_{3}\right)^{+}\right] ; \mathrm{K}_{1}=3.5 \times 10^{-3}\) \(\left[\mathrm{Ag}\left(\mathrm{NH}_{3}\right)\right]^{+}+\mathrm{NH}_{3} \rightleftharpoons\left[\mathrm{Ag}\left(\mathrm{NH}_{3}\right)\right]^{+} ; \mathrm{K}_{2}=1.7 \times 10^{-3}\) Then the formation constant of \(\left[\mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{2}\right]^{+}\)is (a) \(6.08 \times 10^{-6}\) (b) \(6.08 \times 10^{6}\) (c) \(6.08 \times 10^{-9}\) (d) None

When \(0.1\) mole of \(\mathrm{CH}_{3} \mathrm{NH}_{2}\) (ionization constant \(\mathrm{K}_{\mathrm{b}}=5 \times 10^{-4}\) ) is mixed with \(0.08 \mathrm{~mol} \mathrm{HCl}\) and the volume is made up of 1 litre. Find the \(\left[\mathrm{H}^{+}\right]\)of resulting solution. (a) \(8 \times 10^{-2}\) (b) \(2 \times 10^{-11}\) (c) \(1.23 \times 10^{-4}\) (d) \(8 \times 10^{-11}\)

If \(\mathrm{Ag}^{+}+2 \mathrm{NH}_{3} \rightleftharpoons \mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{2}^{+} ; \mathrm{K}_{1}=1.8 \times 10^{7}\) \(\mathrm{Ag}^{+}+\mathrm{Cl} \rightleftharpoons \mathrm{AgCl} ; \mathrm{K}_{2}=5.6 \times 10^{9}\) Then for \(\mathrm{AgCl}+2 \mathrm{NH}_{3} \rightleftharpoons\left[\mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{2}\right]^{+}+\mathrm{Cl}^{-}\), Equilibrium constant will be (a) \(0.32 \times 10^{-2}\) (b) \(3.11 \times 10^{2}\) (c) \(10.08 \times 10^{16}\) (d) \(1.00 \times 10^{-17}\)

There sparingly soluble salts \(\mathrm{A}_{2} \mathrm{X}, \mathrm{AX}\) and \(\mathrm{AX}_{3}\) have the same solubility product. Their solubilities will be in the order (a) \(\mathrm{AX}_{3}>\mathrm{AX}>\mathrm{A}_{2} \mathrm{X}\) (b) \(\mathrm{AX}_{3}>\mathrm{A}_{2} \mathrm{X}>\mathrm{AX}\) (c) \(\mathrm{AX}>\mathrm{AX}_{3}>\mathrm{A}_{2} \mathrm{X}\) (d) \(\mathrm{AX}>\mathrm{A}_{2} \mathrm{X}>\mathrm{AX}_{3}\)

Which of the following solution(s) have \(\mathrm{pH}\) between 6 and \(7 ?\) 1\. \(2 \times 10^{-6} \mathrm{M} \mathrm{NaOH}\) 2\. \(2 \times 10^{-6} \mathrm{M} \mathrm{HCl}\) 3\. \(10^{-8} \mathrm{M} \mathrm{HCl}\) 4\. \(10^{-13} \mathrm{M} \mathrm{NaOH}\) (a) 1,2 (b) 2,3 (c) 3,4 (d) \(2,3,4\)

What is the \(\mathrm{pH}\) value at which \(\mathrm{Mg}(\mathrm{OH})\), begins to precipitate from a solution containing \(0.10 \mathrm{M} \mathrm{Mg}^{+2}\) ion? Ksp of \(\mathrm{Mg}(\mathrm{OH})_{2}\) is \(1 \times 10^{-11}\). (a) 3 (b) 6 (c) 9 (d) 11

50 litres of \(0.1 \mathrm{M} \mathrm{HCl}\) are mixed with 50 litres of \(0.2\) \(\mathrm{M} \mathrm{NaOH}\). The POH of the resulting solution is (a) \(12.70\) (b) \(12.34\) (c) \(8.7\) (d) \(4.2\)

The \(\mathrm{pH}\) of \(0.05 \mathrm{M}\) aqueous solution of diethylamine is 12\. Its \(\mathrm{K}_{b}\) is (a) \(2 \times 10^{-3}\) (b) \(2.5 \times 10^{-3}\) (c) \(3 \times 10^{-3}\) (d) \(4.5 \times 10^{-3}\)

The approximate \(\mathrm{pH}\) of a solution formed by mixing equal volumes of solutions of \(0.1 \mathrm{M}\) sodium propionate and \(0.1 \mathrm{M}\) propanoic acid (the dissociation constant of propanoic acid is \(1.3 \times 10^{-5} \mathrm{~mol} \mathrm{dm}^{-3}\) ) will be (a) \(2.45\) (b) \(4.89\) (c) \(5.98\) (d) \(6.89\)

The dissociation constant of acetic acid is \(1.6 \times 10^{-5}\). The degree of dissociation \((\alpha)\) of \(0.01 \mathrm{M}\) acetic acid in the presence of \(0.1 \mathrm{M} \mathrm{HCl}\) is equal to (a) \(0.4\) (b) \(0.026\) (c) \(1.6\) (d) \(0.016\)

If the equilibrium constant of the reaction of weak acid HA with strong base is \(10^{9}\), then \(\mathrm{pH}\) of \(0.1 \mathrm{M} \mathrm{NaA}\) is (a) 3 (b) 9 (c) 7 (d) 6

If \(\mathrm{Ksp}\) of \(\mathrm{Al}(\mathrm{OH})_{3}\) is \(1.0 \times 10^{-15} \cdot \mathrm{M}\). Find at what \(\mathrm{pH}\) does \(1.0 \times 10^{-3} \cdot \mathrm{M} \mathrm{Al}^{3+}\) precipitate on the addition of buffer of \(\mathrm{NH}_{4} \mathrm{Cl}\) and \(\mathrm{NH}_{4} \mathrm{OH}\) solution. (a) 10 (b) \(10.5\) (c) 11 (d) 12

Acetic acid and aq. \(\mathrm{NH}_{3}\) are weak monobasic acid and weak monobasic base respectively and \(\mathrm{Ka}\) of acetic acid is equal to \(\mathrm{K}_{\mathrm{b}}\) of aq. \(\mathrm{NH}_{3}\). Which of the following statements are incorrect? (1) If acetic acid is exactly neutralized by aq. \(\mathrm{NH}_{3}\) then \(\mathrm{pH}\) of resulting solution is equal to \(1 / 2\) pkw. (2) All the above mixing would result solution having \(\mathrm{pH}=7\) at \(25^{\circ} \mathrm{C}\) (3) If acetic acid is exactly half neutralized by \(\mathrm{NaOH}\), then \(\mathrm{pH}\) of resulting solution is equal to \(\mathrm{pKa}\). (4) If aq. \(\mathrm{NH}_{3}\) is exactly half neutralized by HCl, then pOH of resulting solution is equal to \(\mathrm{pK}_{\mathrm{b}}\). (a) 2 and 4 (b) 2 and 3 (c) 1 and 3 (d) 2 only

The solubility of \(\mathrm{CaF}_{2}\) in water at \(298 \mathrm{~K}\) is \(1.7 \times 10^{-3}\) gm per \(100 \mathrm{~cm}^{3} .\) The solubility product of \(\mathrm{CaF}_{2}\) at 298 \(\mathrm{K}\) is (a) \(4.14 \times 10^{-11}\) (b) \(4.14 \times 10^{11}\) (c) \(4.14 \times 10^{-6}\) (d) \(4.14 \times 10^{6}\)

The following acids have been arranged in order or decreasing acid strength: ClOH(I), BrOH(II), IOH(III). Identify the correct order. (a) \(\mathrm{I}>\mathrm{II}>\mathrm{III}\) (b) \(\mathrm{III}>\mathrm{I}>\mathrm{II}\) (c) \(\mathrm{II}>\mathrm{III}>\mathrm{I}\) (d) \(\mathrm{III}>\mathrm{II}>\mathrm{I}\)

The solubility product of \(\mathrm{PbI}_{2}\) is \(7.47 \times 10^{-9}\) at \(15^{\circ} \mathrm{C}\) and \(1.39 \times 10^{8}\) at \(25^{\circ} \mathrm{C}\). The molar heat of solution of \(\mathrm{PbI}_{2}\) is (use \(\log 1.86=0.2695\) ) (a) \(44.29 \mathrm{~kJ} / \mathrm{mol}\) (b) \(46.25 \mathrm{~kJ} / \mathrm{mol}\) (c) \(29.37 \mathrm{~kJ} / \mathrm{mol}\) (d) \(21.15 \mathrm{~kJ} / \mathrm{mol}\)

The correct order of relative basic strength of the following is (a) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}>\mathrm{CH} \equiv \mathrm{C}^{-}>-\mathrm{OH}\) (b) \(\mathrm{CH} \equiv \mathrm{C}^{-}>-\mathrm{OH}>\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}\) (c) \(\mathrm{CH} \equiv \mathrm{C}^{-}>\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}>-\mathrm{OH}\) (d) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}>\mathrm{OH}^{-}>\mathrm{CH} \equiv \mathrm{C}^{-}\)

At what concentration of \(\mathrm{CH}_{3} \mathrm{COOH}\) will the \(\left[\mathrm{H}^{+}\right]\) obtained will be same as that obtained from \(10^{-2} \mathrm{M}\) \(\mathrm{HCOOH},\left(\mathrm{Ka}\left(\mathrm{CH}_{3} \mathrm{COOH}\right)=10^{-5}, \mathrm{Ka}(\mathrm{HCOOH})=10^{-4}\right)\) (a) \(10 \mathrm{M}\) (b) \(5 \mathrm{M}\) (c) \(10^{-1} \mathrm{M}\) (d) \(6 \mathrm{M}\)

When \(\mathrm{NH}_{4} \mathrm{Cl}\) is added to an aqueous solution of \(\mathrm{NH}_{4} \mathrm{OH}\) (a) Conc. of \(\left[\mathrm{OH}^{-}\right]\)ions decreases. (b) Conc. of \(\left[\mathrm{OH}^{-}\right]\)ions increases. (c) Conc. of \(\left[\mathrm{NH}_{4}^{+}\right]\)ions as well as conc. \(\left[\mathrm{OH}^{-}\right]\)ions increase. (d) Conc. of \(\left[\mathrm{NH}_{4}^{+}\right]\)ions decreases.

\(500 \mathrm{ml}\) of \(0.2 \mathrm{M} \mathrm{HCl}\) is mixed with \(500 \mathrm{ml}\) of \(0.2 \mathrm{M}\) \(\mathrm{CH}_{3} \mathrm{COOH} .25 \mathrm{ml}\) of the mixture is titrated with \(0.1\) M \(\mathrm{NaOH}\) solution. By how many units does the \(\mathrm{pH}\) change from the start to the stage when \(\mathrm{HCl}\) is just completely neutralized. \(\mathrm{K}_{\text {, for acetic acid }}=2.0 \times 10^{-5}\). (a) \(3.7\) (b) \(4.4\) (c) \(2.0\) (d) \(3.0\)

When \(60 \mathrm{ml}\) of \(0.1 \mathrm{M} \mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}\) is mixed with \(40 \mathrm{ml}\) of \(0.125 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}, \mathrm{CaCO}_{3}\) precipitates. If \(\mathrm{K}_{\text {sp }}\) of \(\mathrm{CaCO}_{3}\) is \(5 \times 10^{-9} \mathrm{M}^{2}\), the \(\left[\mathrm{CO}_{3}^{2-}\right]\) in the resulting solution is (a) \(5 \times 10^{-8} \mathrm{M}\) (b) \(5 \times 10^{-9} \mathrm{M}\) (c) \(5 \times 10^{-6} \mathrm{M}\) (d) \(5 \times 10^{-7} \mathrm{M}\)

\(100 \mathrm{ml}\) of \(0.3 \mathrm{M} \mathrm{NH}_{4} \mathrm{OH}\) is mixed with \(100 \mathrm{ml}\) of \(0.2\) M \(\mathrm{NaOH} . \mathrm{K}_{b}\) of \(\mathrm{NH}_{4} \mathrm{OH}\) is \(1.8 \times 10^{-5} .\) The degree of dissociation of \(\mathrm{NH}_{4} \mathrm{OH}\) is (a) \(1.02 \times 10^{-2}\) (b) \(1.8 \times 10^{-5}\) (c) \(1.8 \times 10^{-4}\) (d) \(1.02 \times 10^{-4}\)

The ionization constant of \(\left[\mathrm{NH}_{4}^{+}\right]\)in water is \(5.6 \times 10^{-10}\) at \(25^{\circ} \mathrm{C}\). The rate constant for the reaction of \(\left[\mathrm{NH}_{4}^{+}\right]\) and \(\left[\mathrm{OH}^{-}\right]\)to form \(\mathrm{NH}_{3}\) and \(\mathrm{H}_{2} \mathrm{O}\) is \(3.4 \times 10^{10}\) litmol \(^{-1}\) \(\sec ^{-1}\) at \(25^{\circ} \mathrm{C}\). The rate constant for the proton transfer form water to \(\mathrm{NH}_{3}\) in lit \(\mathrm{mol}^{-1} \mathrm{sec}^{-1}\) is (a) \(6.07 \times 10^{5}\) (b) \(6.07 \times 10^{-5}\) (c) \(6.07 \times 10^{-3}\) (d) \(6.07 \times 10^{-4}\)

Equilibrium constant of \(\mathrm{NH}_{4}^{+}\)to \(\mathrm{NH}_{3}\) and \(\mathrm{H}^{+}\)is \(10^{-10}\). The rate constant for \(\mathrm{NH}_{4}^{+}+\mathrm{OH}^{-} \rightarrow \mathrm{NH}_{3}+\mathrm{H}_{2} \mathrm{O}\) is \(10^{10} .\) The rate constant for \(\mathrm{NH}_{3}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NH}_{4}^{+}+\mathrm{OH}^{-}\)is (a) \(10^{5}\) (b) \(10^{6}\) (c) \(10^{8}\) (d) \(10^{9}\)

An acid base indicator has \(\mathrm{K}_{\mathrm{a}}=3 \times 10^{-5} .\) The acid form of the indicator is red and the basic form is blue. By how much must the \(\mathrm{pH}\) change in order to change the indicator from \(75 \%\) red to \(75 \%\) blue \((\log 3=0.4770)\) (a) \(0.95\) (b) \(2.3\) (c) \(0.75\) (d) 5

A solution of benzoic acid (a weak monobasic acid) is titrated with \(\mathrm{NaOH}\). The \(\mathrm{pH}\) of the solution is \(4.2\) when half of the acid is neutralized. Dissociation constant of the acid is (a) \(3.2 \times 10^{-5}\) (b) \(6.42 \times 10^{-4}\) (c) \(6.31 \times 10^{-5}\) (c) \(8.7 \times 10^{-8}\)

Which of the following composition shows maximum buffer capacity? (a) \(0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}+0.2 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONa}\) (b) \(0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}+0.15 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONa}\) (c) \(0.05 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}+0.15 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONa}\) (d) \(0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}+0.12 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONa}\)

The \(\mathrm{pH}\) of a solution containing \(0.1 \mathrm{~mol}\) of \(\mathrm{CH}_{3} \mathrm{COOH}\), \(0.2\) mol of \(\mathrm{CH}_{3} \mathrm{COONa}\) and \(0.05 \mathrm{~mol}\) of \(\mathrm{NaOH}\) in \(1 \mathrm{~L}\). \(\left(\mathrm{pK}_{\mathrm{a}}\right.\) of \(\mathrm{CH}_{3} \mathrm{COOH}=4.74\) and \(\left.\log 5=0.7\right)\) (a) \(4.56\) (b) \(5.44\) (c) \(5.04\) (d) \(3.74\)

The dissociation constant of monobasic acids A, B and \(\mathrm{C}\) are \(10^{-4}, 10^{-6}\) and \(10^{-10}\) respectively. The concentration of each monobasic acid is \(0.1 \mathrm{M}\). Which of the following has been arranged in increasing order of \(\mathrm{pH}\) ? (a) \(C

\(18 \mathrm{ml}\) of mixture of acetic acid and sodium acetate required \(6 \mathrm{ml}\) of \(0.1 \mathrm{M} \mathrm{NaOH}\) for neutralization of the acid and \(12 \mathrm{ml}\) of \(0.1 \mathrm{M} \mathrm{HCl}\) for reaction with salt separately. If \(\mathrm{pK}_{\mathrm{a}}\) of the acid is \(4.75\), what is the \(\mathrm{pH}\) of the mixture? (a) \(5.05\) (b) \(4.75\) (c) \(4.5\) (d) \(4.6\)

Solubility of \(\mathrm{AgCl}\) in water, \(0.01 \mathrm{M} \mathrm{CaCl}_{2}, 0.01 \mathrm{M}\) \(\mathrm{NaCl}\) and \(0.05 \mathrm{M} \mathrm{AgNO}_{3}\) are \(\mathrm{S}_{1}, \mathrm{~S}_{2}, \mathrm{~S}_{3}\) and \(\mathrm{S}_{4}\) respec- tively then (a) \(\mathrm{S}_{1}>\mathrm{S}_{2}=\mathrm{S}_{3}>\mathrm{S}_{4}\) (b) \(\mathrm{S}_{1}>\mathrm{S}_{3}>\mathrm{S}_{4}>\mathrm{S}_{2}\) (c) \(\mathrm{S}_{1}<\mathrm{S}_{2}<\mathrm{S}_{3}<\mathrm{S}_{4}\) (d) \(\mathrm{S}_{1}>\mathrm{S}_{3}>\mathrm{S}_{2}>\mathrm{S}_{4}\)

A buffer solution is prepared by mixing \(10 \mathrm{~mL}\) of \(1.0\) M acetic and \(20 \mathrm{~mL}\) of \(0.5 \mathrm{M}\) sodium acetate and then diluted to \(100 \mathrm{~mL}\) with distilled water. If the pKa of \(\mathrm{CH}_{3} \mathrm{COOH}\) is \(4.76\), what is the \(\mathrm{pH}\) of the buffer solution prepared? (a) \(5.21\) (b) \(4.76\) (c) \(4.34\) (d) \(5.35\)

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) \(3.42\)

Calculate the ratio of \(\mathrm{pH}\) of a solution containing 1 mole of \(\mathrm{CH}_{3} \mathrm{COONa}+1\) mole of HCl per litre to that of a solution containing 1 mole of \(\mathrm{CH}_{3} \mathrm{COONa}+1\) mole of \(\mathrm{CH}_{3} \mathrm{COOH}\) per litre. (a) \(\frac{2}{1}\) (b) \(\frac{1}{2}\) (c) \(\frac{2}{3}\) (d) \(\frac{3}{2}\)

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 \(\left[\mathrm{K}_{\mathrm{sp}}(\mathrm{AgOH})=10^{-10}\right]\) (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 \(\mathrm{K}=3.0 \times 10^{-5} .\) 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 \([\mathrm{Cl}]\) is \(\left(\mathrm{K}_{\mathrm{sp}}\right.\) of \(\mathrm{AgCl}=10^{-12}, \mathrm{~K}_{\$}\) 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 \(\mathrm{NaW}\), NaX, \(\mathrm{NaY}\) and \(\mathrm{NaZ}\) had \(\mathrm{pH} 7.0,9.0,10.0\) and \(11.0\) respectively. When each solution is \(0.1 \mathrm{M}\), the strongest acid is (a) HW (b) HX (c) HY (d) \(\mathrm{HZ}\)

Silver acetate is a slightly soluble salt of a weak acid \(\left(\mathrm{K}_{\mathrm{a}}=1.75 \times 10^{-5}\right) .\) At \(20^{\circ} \mathrm{C}, 100 \mathrm{~g}\) of water dissolves \(1.04 \mathrm{~g}\) of crystalline silver acetate. The density of saturated solution of silver acetate at \(20^{\circ} \mathrm{C}\) is \(1.01 \mathrm{~g} / \mathrm{cc}\). The solubility product constant for silver acetate at \(20^{\circ} \mathrm{C}\) (a) \(2.43 \times 10^{-3}\) (b) \(3.87 \times 10^{-3}\) (c) \(7.74 \times 10^{-5}\) (d) \(1.35 \times 10^{-5}\)