CBSE Questions for Class 11 Medical Chemistry Equilibrium Quiz 14 - MCQExams.com

At $$90^{ \circ  }C$$, pure water has $$[{ H }_{ 3 }O^{ + }]={ 10 }^{ -6.7 }\ mol/lit$$. What is the value of $${ K }_{ W }$$ at $${ 90 }^{ \circ  }C :-$$
  • $${ 10 }^{ -6 }$$
  • $${ 10 }^{ -12 }$$
  • $${ 10 }^{ -14 }$$
  • $${ 10 }^{ -13.4 }$$
Which of the following will not function as buffer solution?
  • $${\text{Na}}{{\text{H}}_{\text{2}}}{\text{P}}{{\text{O}}_{\text{4}}}{\text{ + N}}{{\text{a}}_{\text{2}}}{\text{HP}}{{\text{O}}_{\text{4}}}\left( {{\text{1:1}}\,{\text{Molar}}\,{\text{Ratio}}} \right)$$
  • $${\text{N}}{{\text{H}}_4}{\text{Cl + NaOH}}\left( {{\text{2:1}}\,{\text{Molar}}\,{\text{Ratio}}} \right)$$
  • $${\text{HCOOH + NaOH}}\left( {{\text{1:1}}\,{\text{Molar}}\,{\text{Ratio}}} \right)$$
  • $${\text{HCOOH + HCOONa}}\left( {{\text{1:1}}\,{\text{Molar}}\,{\text{Ratio}}} \right)$$
In which of the following solution of electrolyte, ionic equilibrium is set up?
  • $$H_{2}SO_{4}$$
  • $$HCl$$
  • $$NaOH$$
  • $$HCN$$
Which of the following is a buffer solution? 
  • 500 mL of 0.1 N CH$$_3$$COOH +500 mL of 0.4 N NaOH
  • 500 mL of 0.1 N CH$$_3$$COOH +500 mL of 0.1 N HCl
  • 500 mL of 0.1 N CH$$_3$$COOH +500 mL of 0.2 N NaOH
  • 500 mL of 0.1 N CH$$_3$$COOH +500 mL of 0.3N NaOH
On adding NaCl solution to the saturated solution of $$PbCl_2$$ then the concentration of :
  • $$Pb^{2+}$$ will increase
  • $$Cl^-$$ will decrease
  • $$Pb^{2+}$$ will decrease
  • Ions will remain unaltered
The ionic product of water at $$ 25^oC $$ is $$ 10^{-14} $$ The ionic product at $$ 90^oC $$ will be 
  • $$ 1 \times 10^{-20} $$
  • $$ 1 \times 10^{-12} $$
  • $$ 1 \times 10^{-14} $$
  • $$ 1 \times 10^{-16} $$
In a buffer solution the ratio of concentration of $${\text{N}}{{\text{H}}_{\text{4}}}{\text{Cl}}\,\,{\text{and}}\,{\text{N}}{{\text{H}}_{\text{4}}}{\text{OH}}\,\,{\text{is}}\,\,{\text{1:1}}$$ when it changes in 2:1 what will be the value of pH of buffer:-
  • Increase
  • Decrease
  • No effects
  • N. O. T.
A hydrogen electrode placed in a buffer solution of NaCl and HCN in the ratio of X:Y and Y:X has an oxidation electrode potential values $${E_1}\,\,and\,\,{E_2}$$ volts respectively at $${25^0}C$$. The pKa value of HCN is
  • $$\frac{{({E_1} + {E_2})}}{{0.118}}$$
  • $$ - \frac{{({E_1} + {E_2})}}{{0.118}}$$
  • $$\frac{{({E_1} - {E_2})}}{{0.118}}$$
  • $$\frac{{({E_2} - {E_1})}}{{0.118}}$$
If the degree of ionization of water is 1.8 x $$10^{-9}$$ at a given temperature. Its ionic product will be 
  • 1.8 x $$10^{-16}$$
  • 1 x $$10^{-14}$$
  • 1 x $$10^{-16}$$
  • 1.67 x $$10^{-14}$$
$$2{H_2}O\leftrightharpoons {H_3}{O^ + } + O{H^ - },{K_w} = 1\times {10^{ - 14}}$$ at $${25^ \circ }C$$ hence $$K_a$$ is :
  • $$1\times 10^{-14}$$
  • $$18\times 10^{-17}$$
  • $$5.55\times 10^{-3}$$
  • $$1.00\times 10^{-7}$$
The dissociation constant of a weak acid is $$1.0 \times { 10 }^{ -5 }$$, the equilibrium constant for its reaction with strong base is 
  • $$1.0 \times { 10 }^{ -5 }$$
  • $$1.0 \times { 10 }^{ 9 }$$
  • $$1.0 \times { 10 }^{ 7 }$$
  • $$1.0 \times { 10 }^{ 14 }$$
One litre of water contains $$10 ^ { - 7 }$$ mole of $$H ^ { + }$$ ions. Degree of ionisation of water is:
  • $$1.8 \times 10 ^ { - 7 } \%$$
  • $$0.8 \times 10 ^ { - 9 } \%$$
  • $$3.6 \times 10 ^ { - 9 } \%$$
  • $$3.6 \times 10 ^ { - 7 } \%$$
Aqueous solution of NaCl is neutral because 
  • $$Na^{ + }$$ undergoes hydrolysis
  • Cl undergoes hydrolysis
  • Both $$Na^{ + }$$ and Cl undergo hydrolusis
  • Does not undergo hydrolysis
Which of the following may be regarded as buffer solution? 
  • 50 ml of 0.1 M acetic acid + 50 ml of 0.05 M $$NaOH$$
  • 50 ml of 0.05 ammonia + 50 ml of 0.1 M $$HCl$$
  • 25 ml of 0.1 M acetic acid + 50 ml of 0.1 M $$NaOH$$
  • 50 ml of 0.1 ammonia + 50 ml of 0.05 M $$HCl$$
The total number of different kind of buffer obtained during the titration of $${ H }_{ 3 }{ PO }_{ 4 }$$ with NaOH are:- 
  • 3
  • 1
  • 2
  • 0
Select the correct acid-base equilibrium.
  • $$\mathrm { HNO } _ { 3 } + \mathrm { HF } \rightleftharpoons \mathrm { H } _ { 2 } \mathrm { NO } _ { 3 } ^ { + } + \mathrm { F } ^ { - }$$
  • $$\mathrm { HNO } _ { 3 } + \mathrm { HF } \rightleftharpoons \mathrm { H } _ { 2 } \mathrm { F } ^ { + } + \mathrm { NO } _ { 3 } ^ { - }$$
  • $$\mathrm { CH } _ { 3 } \mathrm { COOH } + \mathrm { NH } _ { 3 } \rightleftharpoons \mathrm { CH } _ { 3 } \mathrm { COOH } _ { 2 } ^ { + } + \mathrm { NH } _ { 2 } ^ { + }$$
  • $$\mathrm { HF } + \mathrm { H } _ { 2 } \mathrm { O } \rightleftharpoons \mathrm { H } _ { 2 } \mathrm { F } ^ { + } + \mathrm { OH } ^ { - }$$
$$HCOOH$$ and $$CH_3COOH$$ solutions have equal $$pH$$. If $$\cfrac{K_1}{K_2}$$ (ratio of ionisation constants of acids) is 4, their molar concentration ratio will be:
  • 2
  • 0.5
  • 4
  • 0.25
At $$90 ^ { \circ } C ,$$ pure water has $$\left[ \mathrm { H } _ { 3 } \mathrm { O } ^ { + } \right] = 10 ^ { - 6 } \mathrm { mol }$$ litre $$^ { - 1 } .$$ The value of $$K _ { w }$$ at $$90 ^ { \circ } \mathrm { C }$$ is:
  • $$10 ^ { - 6 }$$
  • $$10 ^ { - 12 }$$
  • $$10 ^ { - 14 }$$
  • $$10 ^ { - 8 }$$
Hydrogen ion concentration of an aqueous solution is $$1 \times 10^{-4}M$$. The solution is diluted with equal volume of water. Hydroxyl ion concentration of the resultant solution in terms of mol $$dm^{-3}$$ is __________.
  • $$1 \times 10^{-8}$$
  • $$1 \times 10^{-6}$$
  • $$2 \times 10^{-10}$$
  • $$0.5 \times 10^{-10}$$
If $$1M$$ $$C{H_3}COONa$$ is added to $$1M$$ $$C{H_3}COOH$$, then:
  • $$pH$$ of the solution increases
  • $$pH$$ decreases
  • $$pH$$ does not change
  • cannot be predicted
The dissociation constants for acetic acid  and HCN at $$25^{0}$$C are $$1 . 5 \times 10^{-5}$$  and $$4 . 5 \times 10 ^{-10} $$, respectively. The equilibrium constant for the equilibrium $$CN^{-} + CH_{3}COOH \leftrightharpoons HCN + CH_{3}COO^{-}$$ would be :
  • $$3\times10^{4}$$
  • $$3\times10^{5}$$
  • $$3\times10^{-5}$$
  • $$3\times10^{-4}$$
At $${ 25 }^{ \circ  }C$$ the dissociation constant of a base , BOH, is $$1.0\times { 10 }^{ -12 }$$. The concentration of hydroxyl ions in 0.01 M aqueous solution of the base would be
  • $$1.0\times { 10 }^{ -6 }{ molL }^{ -1 }$$
  • $$1.0\times { 10 }^{ -7 }{ molL }^{ -1 }$$
  • $$2.0\times { 10 }^{ -6 }{ molL }^{ -1 }$$
  • $$1.0\times { 10 }^{ -5 }{ molL }^{ -1 }$$
A solution is saturated with respect to $$AgSCN$$ as well as $$AgBr$$. The concentration of $$Ag^{+}$$ in the solution would be:
($$ K_{sp}$$ for $$AgSCN = 1.2 \times 10^{-12}$$ and for $$AgBr = 5 \times 10^{-13}$$) 
  • $$1.3 \times 10^{-5}$$
  • $$1.3 \times 10^{-12}$$
  • $$1.3 \times 10^{-6}$$
  • $$1.3 \times 10^{-8}$$
Which of the following salt evolve(s) $${ N }_{ 2 }$$ gas on heating ?
  • $$\left( { NH }_{ 4 } \right) _{ { 2 } }{ CrO }_{ 4 }$$
  • $${ NH }_{ 4 }{ NO }_{ 2 }$$
  • $${ NH }_{ 4 }{ NO }_{ 3 }$$
  • $$\left( { NH }_{ 4 } \right) _{ { 2 } }{ CO }_{ 3 }$$
Which of following salt solution will impart greenish colour ?
  • $$ K_2Cr_2O_7 $$
  • $$ ZnCl_2 $$
  • $$ K_2MnO_4 $$
  • $$ K_2CrO_4 $$
10 ml of 0.2 M $$ AgNO_3 $$ is mixed with 10 ml of 0.1 M $$NaCl$$. What is the concenctration of $$ Cl^- $$ in the resulting solution $$[ K_{sp} (AgCl) = 10^{-10} M^2] $$
  • $$ 10^{-5} M $$
  • $$ 10^{-9} M $$
  • $$ 2 \times 10^{-9} M $$
  • $$ 10^{-8} M $$
For preparing a buffer solution of pH = 7.0, which buffer system you will choose?
  • $$H_3PO_4,H_2PO_4^-$$
  • $$H_2PO_4^-, HPO_4^{2-}$$
  • $$HPO^{2-}_4, PO^{3-}_4$$
  • $$H_3PO_4, PO_4^{3-}$$
The percentage of pyridine $$\left( { C }_{ 5 }{ H }_{ 5 }N \right) $$ that forms pyridinium ion $$\left( { C }_{ 5 }{ H }_{ 5 }{ N }^{ + }H \right) $$ in a 0.10 m aqueous pyridine solution $$\left( K_{ b } \ for\ { C }_{ 5 }{ H }_{ 5 }N=1.7\times { 10 }^{ -9 } \right) $$ is:
  • 0.0060%
  • 0.013%
  • 0.77%
  • 1.6%
A weak acid react with strong base, ionisation constant of weak acid is $${ 10 }^{ -4 }$$. Find out equilibrium constant for this reaction. 
  • $${ 10 }^{ -10 }$$
  • $${ 10 }^{ 10 }$$
  • $${ 10 }^{ -9}$$
  • $${ 10 }^{ 9}$$
Which statement is/are correct-
  • If $$0.1\ M$$ $$ CH_3COOH $$ aqueous solution $$ ( K_a = 1.8 \times 10^{-5} ) $$ is diluted at $$ 2560^o C $$, then $$ [H^+] $$ will increase
  • On heating a sample of pure water $$ [H^+] $$ and $$ [OH^-] $$ increases but the sample still remains neutral
  • $$ 10^{-4}\ M$$ $$HCl$$ solution is less acidic than $$0.1\ M$$ $$HCN$$ $$ ( K_a HCN = 10^{-5} ) $$
  • $$ 10^{-8}\ M $$ $$HCl$$ aqueous solution will have pH exactly equal to 8
The self ionisation constant of $$\mathrm { NH } _ { 3 }$$ at $$50 ^ { \circ } \mathrm { C }$$  is given by $$\mathrm { K } _ { \mathrm { NH } _ { 3 } } = \left[ \mathrm { NH } _ { 4 } ^ { + } \right] \left[ \mathrm { NH } _ { 2 } ^ { - } \right] = 10 ^ { - 30 }$$. How many $$N H _ { 2 } ^ { - }$$ ions are present per $$\mathrm { cm } ^ { 3 }$$ of pure liquid $$\mathrm { NH } _ { 3 }$$?
  • $$6 \times 10 ^ { 6 }$$
  • $$6 \times 10 ^ { 5 }$$
  • $$6 \times 10 ^ { - 5 }$$
  • $$6 \times 10 ^ { - 6 }$$
The dissociation constant of an acid HA is $$1 \times 10 ^ { - 5 }$$. The pH of 0.1 molar solution of the acid will be approximately:
  • 3
  • 5
  • 1
  • 6
The silicate anion in the mineral kinetic is a chain of three $$SiO_4^{4^-}$$ tetrahedral that shares conners with adjacent tetrahedral. The mineral also contains $$Ca$$ icon $$Cu$$ ions and water molecules in a 1:1:1 ratio mineral represented as:
  • $$CaCu_2Si_{ 3 }O_{ 10 }.H_{ 2 }O$$
  • $$CaCuSi_{ 3 }O_{ 10 }.H_{ 2 }O$$
  • $$Ca_{ 2 }Cu_{ 2 }Si_{ 3 }O_{ 10 }.2H_{ 2 }O$$
  • None of these
Which of the following is ionic?
  • $$HCl$$
  • $$CHCl_3$$
  • $$IF_5$$
  • $$KI$$
For which salt the $$\mathrm { pH }$$ of its solution does not change with dilution?
  • $$\mathrm { NH } _ { 4 } \mathrm { Cl }$$
  • $$\mathrm { CH } _ { 3 } \mathrm { COONH } _ { 4 }$$
  • $$\mathrm { CH } _ { 3 } \mathrm { COONa }$$
  • None of these
Consider the following equilibrium.
Liquid $$\rightleftharpoons$$ Vapour
Which of the following relation is correct?
  • $$\dfrac{d ln P}{dT}=\dfrac{\Delta Hv}{RT^2}$$
  • $$\dfrac{d ln G}{dT^2}=\dfrac{\Delta Hv}{RT^2}$$
  • $$\dfrac{d ln P}{dT}=\dfrac{-\Delta Hv}{RT}$$
  • $$\dfrac{d ln P}{dT^2}=\dfrac{-\Delta Hv}{T^2}$$
The $$pH$$ of an aqueous solution of sodium chloride at $$60^{\circ}C$$ is
  • $$7.0$$
  • $$> 7.0$$
  • $$<7.0$$
  • $$0$$
The EMF of cell: $$ H_{2}(g)|$$ Buffer $$ \parallel $$ Normal calmelelectrod, is 0.70 V at $$ 25^{\circ}C,$$ when barometric pressure is 760 mm. What is the pH of the buffer solution? $$ E_{Calomel}^{0} = 0.28 V. [2.303 RTIF = 0.06]$$
  • 3.5
  • 7.0
  • tending to zero
  • tending to 14.0
The dissociation constant of formic acid is $$0.00024$$. The hydrogen ion concentration in $$0.002 M \ HCOOH$$ solution is nearly
  • $$6.93 \times 10^{-4}M$$
  • $$4.8 \times 10^{-7}M$$
  • $$5.8 \times 10^{-4}M$$
  • $$1.4 \times 10^{-4}M$$
The degree of dissociation of pure water at $$25^{\circ}C$$ is found to be $$1.8 \times 10^{-9}$$. The dissociation constant, $$K_{d}$$ of water, at $$25^{\circ}C$$ is
  • $$10^{-14}$$
  • $$1.8 \times 10^{-16}$$
  • $$5.56 \times 10^{-13}$$
  • $$1.8 \times 10^{-14}$$
Which one of the following salts gives aqueous solution which is neutral?
  • $$NaHC{ O }_{ 3 }$$
  • $$NaHS{ O }_{ 4 }$$
  • $$NaCl$$
  • $$\\ Na{ H }_{ 4 }HC{ O }_{ 3 }$$
When ammonia is added to pure water, the concentration of which of the following species already present, will decrease?
  • $$OH^-$$
  • $$H_3O^+$$
  • $$NH_4^+$$
  • None of these
n-caproic acid, $$C_{5}H_{11}COOH$$, found in coconut and palm oil is used in making artificial flavors, has solubility in water equal to $$11.6 g/L$$. The saturated solution has $$pH = 3.0$$. The $$K_{a }$$ of acid is
  • $$10^{-6}$$
  • $$10^{-5}$$
  • $$2 \times 10^{-5}$$
  • $$2 \times 10^{-6}$$
What is $$ [H^+] $$ in mol/L of a solution that is 0.20 M $$ CH_3CCONa $$ and 0.10 M in $$ CH_3COOH $$? 
$$( K_a\ for\ CH_3COOH = 1.8 \times 10^{-5} ) $$ 
  • $$ 3.5 \times 10^{-4} $$
  • $$ 1.1 \times 10^{-5} $$
  • $$ 1.8 \times 10^{-5} $$
  • $$ 9.0 \times 10^{-6} $$
A solution has initially $$0.1 M -HCOOH$$ and $$0.2 M- HCN$$. $$K_{a}$$ of $$HCOOH = 2.56 \times 10^{-4}$$, $$K_{a}$$ of $$HCN = 9.6 \times 10^{-10}$$. The only incorrect statement for the solution is $$(log 2 = 0.3)$$
  • $$[H]^{+} = 1.6 \times 10^{-3} M$$
  • $$[HCOO]^{-} = 1.6 \times 10^{-3} M$$
  • $$[CN]^{-} = 1.2 \times 10^{-7} M$$
  • $$pOH = 2.8$$
Calculate the formation constant for the reaction of a tripositive metal ion with thiocyanate ions to form the monocomplex if the total metal concentration in the solution is $$2 \times 10^{-3} M$$, the total $$SCN^{-}$$ concentration is $$1.51 \times 10^{-3} M$$ and the free $$SCN^{-}$$ concentration is $$1.0 \times 10^{-5} M$$.
  • $$7.55 \times 10^{4}$$
  • $$3 \times 10^{5}$$
  • $$3.33 \times 10^{-6}$$
  • $$1.5 \times 10^{5}$$
Small amount of freshly precipitated magnesium hydroxides are stirred vigorously in a buffer solution containing $$0.25 M$$ of $$NH_{4}Cl$$ and $$0.05 M$$ of $$NH_{4}OH$$. $$[Mg^{2+}]$$ in the resulting solution is ($$K_{b}$$ for $$NH_{4}OH = 2.0 \times 10^{-5}$$ and $$K_{sp}$$ of $$Mg(OH)_{2} = 8.0 \times 10^{-12}$$)
  • $$4 \times 10^{-6} M$$
  • $$2 \times 10^{-6} M$$
  • $$0.5 M$$
  • $$2.0 M$$
A volume of $$1.0 L$$ of solution which was in equilibrium with solid mixture of $$AgCl$$ and $$Ag_{2}CrO_{4}$$ was found to contain $$1 \times 10^{-4}$$ moles of $$Ag^{+}$$ ions, $$1.0 \times 10^{-6}$$ moles of $$CI^{-}$$ ions and $$8.0 \times 10^{-4}$$ moles of $$CrO_{4}^{2-}$$ ions. $$Ag^{+}$$ ions are added slowly to the above mixture (keeping the volume constant) till $$8.0 \times 10^{-7}$$ moles of $$AgCl$$ got precipitated. How many moles of $$Ag_{2}CrO_{4}$$ were precipitated simultaneously?
  • $$7.68 \times 10^{-4}$$
  • $$4.8 \times 10^{-4}$$
  • $$8.0 \times 10^{-4}$$
  • $$7.68 \times 10^{-5}$$
Which one of the following is not an acid salt?
  • $$NaH_2PO_2$$
  • $$NaH_2PO_3$$
  • $$NaH_2PO_4$$
  • $$Na_2HPO_4$$
The solubility of $$AgCN$$ in a buffer solution of $$pH - 3.0$$ is ($$K_{sp}$$ of $$AgCN = 1.2 \times 10^{-16}$$; $$K_{a}$$ of $$HCN = 4.8 \times 10^{-10}$$)
  • $$1.58 \times 10^{-5}M$$
  • $$2.0 \times 10^{-5}M$$
  • $$1.58 \times 10^{-4}M$$
  • $$2.5 \times 10^{-9}M$$
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