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 Multiple Choice QuestionsMultiple Choice Questions

721.

At a particular temperature, the ratio of equivalent conductance to specific conductance of a 0.01 N NaCl solution is

  • 105 cm3

  • 103 cm3

  • 10 cm3

  • 105 cm2


722.

The number of moles of electrons required to deposit 1gm equivalent aluminium (atomic wt. = 27) from a solution of aluminium chloride will be

  • 3

  • 1

  • 4

  • 2


723.

At temperature of 298K, the emf of the following electrochemical cell,

Ag (s) | Ag+ (0.1 M)|| Zn2+ (0.1 M) | Zn (s) will be (Given, E°cell = -1.562 V)

  • -1.532 V

  • -1.503 V

  • 1.532 V

  • -3.06 V


724.

Assertion: Potassium and caesium are used in photoelectric cells.

Reason: Potassium and caesium emit electrons on exposure to light.

  • If both assertion and reason are true and reason is a correct explanation of the assertion.

  • If both the assertion and reason are true but the reason is not a correct explanation of the assertion.

  • If the assertion is true but the reason is false.

  • If both the assertion and reason are false.


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725.

Li occupies a higher position in the electrochemical series of metals as compared to Cu since :

  • the standard reduction potential of Li+/Li is lower than that of Cu2+/Cu

  • the standard reduction potential of Cu2+/Cu is lower than that of Li+/Li

  • the standard oxidation potential of Li+/Li is lower than that of Cu2+/Cu

  • Li is smaller in size as compared to Cu


726.

A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of pH=10 and by passing hydrogen gas around the platinum wire at 1 atm pressure. The oxidation potential of electrode would be

  • 0.059 V

  • 0.59 V

  • 0.118V

  • 1.18V


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727.

At 25°C molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is 9.54 ohm-1cm2 mol-1 and at infinite dilution its molar conductance is 238 ohm-1cm2 mol-1. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is

  • 2.080%

  • 20.800%

  • 4.008%

  • 40.800%


C.

4.008%

Given, molar conductance at 0.1 M concentration,

                  λc = 9.54 Ω-1 cm2mol-1

Molar conductance at infinite dilution,

                 λc= 238Ω-1 cm2 mol-1

We know that, 

degree of ionisation, α =λcλc× 100  = 9.54238 × 100 = 4.008%


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728.

A button cell used in watches functions as following

Zn(s)+Ag2O(s)+H2O (l)  2Ag(s)+Zn2+(aq)+2OH-(aq)IfhalfcellpotentialsareZn2+(aq)+2e-  Zn(s); E° = -0.76 VAg2O(s)+H2O (l)+ 2e- 2Ag(s)+2OH-(aq), E° = 0.34 VThecellpotentialwillbe

  • 1.10 V

  • 0.42 V

  • 0.84 V

  • 1.34 V


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729.

The quantity of electricity needed to separately electrolyze 1 M solution of ZnSO4 , AlCl3 and AgNO3 completely is in the ratio of

  • 2 : 3 : 1

  • 2 : 1 : 1

  • 2 : 1 : 3

  • 2 : 2 : 1


730.

On passing C ampere of current for the time 't' sec through 1 L of 2 (M) CuSO4 solution (atomic weight of Cu= 63. 5), the amount 'm' of Cu (in gram) deposited on cathode will be

  • m = Ct/(63.5 x 96500)

  • m = Ct/(31.25 X 96500)

  • m = (C x 96500)/(31.25 x t)

  • m = (31.25 X C x t)/96500


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