A conductivity cell has a cell constant of 0.5 cm-1. This cell wh

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 Multiple Choice QuestionsMultiple Choice Questions

321.

An aqueous solution containing 6.5 g of NaCl of 90 purity was subjected to electrolysis. After the complete electrolysis, the solution was evaporated to get solid NaOH. The volume of 1 M acetic acid required to neutralise NaOH obtained above is :

  • 1000 cm3

  • 2000 cm3

  • 100 cm3

  • 200 cm3


322.

Corrosion of iron is essentially an electrochemical phenomenon where the cell reactions are :

  • Fe is oxidised to Fe2+ and dissolved oxygen in water is reduced to OH-

  • Fe is oxidised to Fe3+ and H2O is reduced to O22-

  • Fe is oxidised to Fe2+ and H2O is reduced to O22-

  • Fe is oxidised to Fe2+ and H2O is reduced to O2


323.

On the basis of standard electrode potential of redox couples given below, find out which of the following is the strongest oxidising agent.

(E° values : Fe3+ | Fe2+ = +0.77 V; I2(s) | I- = +0.54 V; Cu2+ | Cu = +0.34 V; Ag+ | Ag = +0.80 V)

  • Fe3+

  • I2(s)

  • Cu2+

  • Ag+


324.

Assertion : If standard reduction potential for the reaction Ag+ + e- Ag is 0.80 volt, then for the reaction 2Ag+ + 2e 2Ag, it will be 1.60 volt.

Reason: If concentration of Ag+ ions is doubled, the standard electrode potential is also doubled.

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

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

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


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325.

How many Faradays of electricity are required for the given reaction to occur ?

MnO4- Mn2+

  • 5 F

  • 3 F

  • 1 F

  • 7 F


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326.

A conductivity cell has a cell constant of 0.5 cm-1. This cell when filled with 0.01 M NaCl solution has a resistance of 384 ohms at 25°C. Calculate the equivalent conductance of the given solution.

  • 130.2 Ω-1 cm2 (g eq)-1

  • 137.4 Ω-1 cm2 (g eq)-1

  • 154.6 Ω-1 cm2 (g eq)-1

  • 169.2 Ω-1 cm2 (g eq)-1


A.

130.2 Ω-1 cm2 (g eq)-1

Equivalent conductance, eq = κ × 1000Normalitywhere, κ (specific conductance) = C × la= lR × la = 1382 × 0.5

 = 1.302 × 10-3  ohm-1 cm-1

 eq = 1.302 × 10-3 × 10000.01             = 130.2 ohm-1 cm2 (g eq)-1


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327.

Ionic conductances of H+ and SO42- at infinite dilution are x and y S cm2 equiv-1 . Hence , equivalent conductance of H2SO4 at infinite dilution is :

  • (x + y)

  • 2(x + y)

  • 2x + y

  • x + 2y


328.

In the refining ofsilver by electrolytic method, what will be the weight of 100 g Ag anode if 5A current is passed for hours ? The purity of silver anode is 95% by weight.

  • 42.91 g

  • 57.59 g

  • 13.16 g

  • 36.38 g


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329.

Salt bridge contains :

  • calomel

  • corrosive sublimate

  • agar-agar paste

  • H2O


330.

Assertion : In electrolysis, the quantity of electricity needed for depositing 1 mole of silver is different from that required for 1 mole of copper.

Reason : The molecular weights of silver and copper are different.

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

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

  • If assertion is true but reason is false.

  • If both assertion and reason are false


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