Electrochemistry Part 2 - Conductance of Electrolytic Solutions and Batteries

1.

During electrolysis of conc. H₂SO₄, perdisulphuric acid (H₂S₂O₈), and O₂
form in equimolar amount. The amount of H₂ that will form simultaneously will be :
1. Thrice that of O₂ in moles.
2. Twice that of O₂ in moles.
3. Equal to that of O₂ in moles.
4. Half of that of O₂ in moles.

2.

During discharge of a lead storage cell, the density of sulphuric acid in the cell-
1. Increases.
2. Decreases.
3. Remains unchanged.
4. Initially increases but decreases subsequently.

3.

The specific conductivity of a solution depends upon :
1. Number of ions as well as mobility of ions.
2. Number of ions per cc or (cm³) of solution.
3. Number of ions per cc or (cm³) as well as mobilities of ions.
4. Mobilities of ions.

4.

The molar conductance of $\frac{M}{32}$ solution of a weak monobasic acid is 8.0 ohm^-1 cm²and at infinite dilution is 400 ohm^-1 cm². The dissociation constant of this acid is:

1.	$1.25 \times10^{-5}$	2.	$1.25 \times10^{-6}$
3.	$6.25 \times10^{-4}$	4.	$1.25 \times10^{-4}$

5.

Salt with the highest electrolytic conductivity in solution is :
1. K₂[PtCl₆]
2. [Co(NH₃)₃(NO₂)₃]
3. K₄[Fe(CN)₆]
4. [Co(NH₃)₄]SO₄

6.

The specific conductance of 0.01 M solution of a weak monobasic acid is 0.20 x 10^-3 S cm^-1. The dissociation constant of the acid is-
[Given $Λ_{HA}^{\infty}$ = 400 S ${cm}^{2}$ ${mol}^{- 1}$ ]

1.	$5 \times 10^{-2}$	2.	$2.5 \times 10^{-5}$
3.	$5 \times 10^{-4}$	4.	$2.2 \times 10^{-11}$

7.

At 25°C, molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is 9.54 Ω^-1cm²mol^-1 and at infinite dilution, its molar conductance is 238 Ω^-1cm²mol^-1. The degree of ionization of ammonium hydroxide at the same concentration and temperature is:
1. 2.080 %
2. 20.800 %
3. 4.008 %
4. 40.800 %

8.

The specific conductance of a 0.1 M KCl solution at 23 $° C$ is 0.012 $Ω^{- 1} {cm}^{- 1}$ .
The resistance of the cell containing the solution at the same temperature was found to be 55 $Ω$ . The cell constant will be:
1. 0.142 cm^–1
2. 0.66 cm^–1
3. 0.918 cm^–1
4. 1.12 cm^–1

9.

The specific conductivity of a saturated solution of KI₃ is 4.59 × 10^-6 ohm^-1 cm^-1 and it's molar conductance is 1.53 ohm^-1 cm² mol^-1. The K_sp Of KI₃ will be :
1. 4 x 10^-12
2. 27 x 27 x 10^-9
3. 9 x 10^-6
4. 4 x 10^-6

10.

The following values of limiting molar conductivities are provided:
$λ_{m}^{0} (H_{2} S O_{4}) = x S c m^{2} m o l^{- 1}$
$λ_{m}^{0} (K_{2} S O_{4}) = y S c m^{2} m o l^{- 1}$
$λ_{m}^{0} (C H_{3} C O O K) = z S c m^{2} m o l^{- 1}$
$λ_{m}^{0} (i n S c m^{2} m o l^{- 1}) f o r C H_{3} C O O H$ will be:
1. $x - y + 2 z$
2. $x + y + z$
3. x-y+z
4. $\frac{(x - y)}{2} + z$

11.

The conductivity of 0.00241 M acetic acid is 7.896 × 10^–5 S cm^–1. If $Λ_{m}^{0}$ for acetic acid is 390.5 S cm² mol^–1, the dissociation constant will be
1. $2.45 \times 10^{-5} \mathrm{~mol} \ \mathrm{~L}^{-1} $
2. $1.86 \times 10^{-5} \mathrm{~mol} \ \mathrm{L^{-1}} $
3. $3.72 \times 10^{-5}\mathrm{~mol} \mathrm{~L^{-1}} $
4. $2.12 \times 10^{-5}\mathrm{~mol} \mathrm{~L^{-1}}$

12.

The incorrect statement about an inert electrode in a cell is:

1.	It does not participate in the cell reaction.
2.	It provides a surface either for oxidation or for the reduction reaction.
3.	It provides a surface for the conduction of electrons.
4.	It provides a surface for redox reaction.

13.

The incorrect statement about the solution of electrolytes is:

1.	Conductivity of solution depends upon the size of ions.
2.	Conductivity depends upon the viscosity of solution.
3.	Conductivity does not depend upon the solvation of ions present in solution.
4.	Conductivity of solution increases with temperature.

14.

The cell constant of a conductivity cell-

1.	Changes with the change of electrolyte.
2.	Changes with the change of concentration of electrolyte.
3.	Changes with the temperature of the electrolyte.
4.	Remains constant for a cell.

15. The correct statement about charging of the lead storage battery is:

1.	PbSO₄ anode is reduced to Pb.
2.	PbSO₄ cathode is reduced to Pb.
3.	PbSO₄ cathode is oxidised to Pb.
4.	PbSO₄ anode is oxidised to PbO₂.

16.

$\Lambda _{m(NH_{4}OH)}^{o}$ is equal to -
1. $\Lambda _{m(NH_{4}OH)}^{o} \ + \ \Lambda _{m(NH_{4}Cl)}^{o} \ - \ \Lambda _{m(HCl)}^{o}$
2. $\Lambda _{m(NH_{4}Cl)}^{o} \ + \ \Lambda _{m(NaOH)}^{o} \ - \ \Lambda _{m(NaCl)}^{o}$
3. $\Lambda _{m(NH_{4}Cl)}^{o} \ + \ \Lambda _{m(NaCl)}^{o} \ - \ \Lambda _{m(NaOH)}^{o}$
4. $\ \Lambda _{m(NaOH)}^{o} \ + \ \Lambda _{m(NaCl)}^{o}\ - \ \Lambda _{m(NH_{4}Cl)}^{o}$

17.

Molar conductivities $(\land °_{m})$ at infinite dilution of
NaCl, HCl, and $C H_{3} C O O N a$ are 126.4, 425.9, and 91.0 S cm² mol^–1 respectively.
$(\land °_{m})$ for $C H_{3} C O O H$ will be:

1.	$180.5~S~cm^2~mol^{-1}$	2.	$290.8~S~cm^2~mol^{-1}$
3.	$390.5~S~cm^2~mol^{-1}$	4.	$425.5~S~cm^2~mol^{-1}$

18.

Given the standard electrode potentials:

K⁺/K = –2.93 V

Ag⁺/Ag = 0.80 V

Hg²⁺/Hg = 0.79 V

Mg²⁺/Mg = –2.37 V

Cr³⁺/Cr = – 0.74 V

The correct increasing order of reducing power of the metals is:

1.	Cr < Mg < K < Ag < Hg	2.	Mg < K < Ag < Hg < Cr
3.	K < Ag < Hg < Cr < Mg	4.	Ag < Hg < Cr < Mg < K

19.

Consider the following graph.

The strong electrolyte in the above graph is represented by:
1. X
2. Y
3. Both X and Y
4. Data given is not sufficient to predict.

20.

Consider the following graph of molar conductivity of KCl solution at different concentrations.

The value of limiting molar conductivity for KCl is 150.0 S cm²mol^-1. The value of the slope at point A will be :

1.	120	2.	100
3.	110	4.	None of the above

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1.	\(1.25 \times10^{-5}\)	2.	\(1.25 \times10^{-6}\)
3.	\(6.25 \times10^{-4}\)	4.	\(1.25 \times10^{-4}\)

1.	\(5 \times 10^{-2}\)	2.	\(2.5 \times 10^{-5}\)
3.	\(5 \times 10^{-4}\)	4.	\(2.2 \times 10^{-11}\)

1.	\(180.5~S~cm^2~mol^{-1}\)	2.	\(290.8~S~cm^2~mol^{-1}\)
3.	\(390.5~S~cm^2~mol^{-1}\)	4.	\(425.5~S~cm^2~mol^{-1}\)

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