A cell, with cell constant 0.4 cm-1, has the resistance of 40 ohm

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 Multiple Choice QuestionsMultiple Choice Questions

151.

What is the emf of the cell, whose half cells are given below

Mg2+ + 2e- → Mg(s) E =-2.37 V

Cu2+ + 2e- → Cu(s) E =+0.34 V

  • -2.30V

  • 1.336V

  • 2.17V

  • 2.93V


152.

Zn | Zn2+C = 1 || Cu2+C = 1 | Cu

If the standard reduction potential of zinc electrode and copper half cell is -0.76 V and 0.34 V respectively then the emf will be

  • 1.1 V

  • 1.4 V

  • 1.34 V

  • None of these


153.

Rusting on iron needs

  • dry air

  • air and water

  • distilled water and carbon dioxide

  • oxygen and carbon dioxide


154.

In galvanic cell, the salt bridge is used to

  • complete the circuit

  • reduce the electric resistance in the cell

  • separate cathode from anode

  • carry salts for the chemical reaction


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155.

A cell, with cell constant 0.4 cm-1, has the resistance of 40 ohm of a 0.01 M solution of an electrolyte, then the molar conductivity in ohm-1 cm2 mol-1 will be

  • 104

  • 103

  • 102

  • 1


B.

103

Cell constant = 0.4 cm-1

Resistance = 40 ohm

 Conductivity = 140 ohm-1

Concentration of solution = 0.01 M

Specific conductivity = conductivity × cell constant

                              = 140 ohm-1 × 0.4 cm-1

                              = 0.01 ohm-1 cm-1

   Molar conductivity = Specific conductivity × 1000Concentration (molarity)

                              = 0.01 × 10000.01

                              = 1000 ohm-1 cm2 mol-1


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156.

If the standard elelctrode potential for the cell Zn | Zn2+ (aq) || Cu2+ (aq) | Cu is 1.10 V, then the maximum work done by this cell will be

  • -106.15 kJ

  • -212.30 kJ

  • -318.45 kJ

  • -424.60 kJ


157.

In electrolysis of NaCl when Pt electrode is taken then H2 is liberated at cathode while with Hg electrode it forms sodium amalgam

  • Hg is more inert than Pt

  • more voltage is required to reduce H+ at Hg than at Pt

  • Na is dissolved in Hg while it does not dissolve in Pt

  • concentration of Hions is larger when Pt electrode is taken


158.

On the basis of the information available from the reaction,

43Al + O2  23 Al2O3

G = -827 kJ mol-1 of O2, the minimum emf required to carry out an electrolysis of Al2O3 is (F = 96500 mol-1)

  • 2.14 V

  • 4.28 V

  • 6.42 V

  • 8.56 V


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159.

4.5 g of aluminium (atomic mass 27 u) is deposited at cathode from Al3+ solution by a certain quantity of electric charge. The volume of hydrogen produced at STP from H+ ions in solution by the same quantity of electric charge will be

  • 44.8 L

  • 11.2 L

  • 22.4 L

  • 5.6 L


160.

For the electrolysis of aqua CuSOsolution using inert Pt electrodes, the reaction on anode

  • 2SO42-  S2O32- + 212O2 + 2e-

  • Cu2+ + 2e- → Cu

  • 2H2O  → O2 + 4H++ 4e-

  • 2H+ + 2e- → H2


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