NDA CHEMISTRY QUIZ - 31

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Question 1:

Rusting of iron is faster in saline water than in ordinary water because

  1. Saline water has less concentration of electrolyte than ordinary water
  2. Saline water has greater concentration of electrolyte than ordinary water
  3. Electrolyte decrease the conductance of the solution in contact with metal surface.
  4. Electrolyte increase the conductance of the solution in contact with metal surface.

Question 2:

Calculate the time to deposit 1.5 g of silver at cathode when a current of 1.5 A was passed through the solution of AgNO3. (Molar mass of Ag = 108 g mol-1, 1 F = 96500 C mol -1).

Question 3:

Alkaline medium ________ rusting of iron 

Question 4:

How much charge is required for the reduction of 1 mole of Zn+2 to Zn?

Question 5:

Calculate the time to deposit 1.27 g of copper at cathode when a current of 2 A was passed through the solution of CuS04.(Molar mass of Cu = 63.5 g mol-1, 1 F = 96500 C mol-1)

Question 6:

A current was passed for 5 hours through two electrolytic cells connected in series. The first cell contains AuCl3 and second cell CuSO4 solution. If 9.85 g of gold was deposited in the first cell, what amount of copper gets deposited in the second cell? Given: Atomic mass of Au = 197 amu and Cu = 63.5 amu. 

Question 7:

Iron does not rust even if the zinc coating is broken because

  1. Zinc has lower reduction potential than iron
  2. Iron has lower reduction potential than zinc
  3. Zinc is more reactive than iron
  4. Zinc is less reactive than iron

Question 8:

How many moles of mercury will be produced by electrolysing 1.0 M Hg(NO3)2 solution with a current of 2.00 A for 3 hours? [Hg(NO3)2 = 200.6 g mol-1]

Question 9:

How many coulombs are required to reduce 1 mole Cr2O72- to Cr3+?

Question 10:

Three iron sheets have been coated separately with three metals A , B and C whose standard electrode potential is -0.46V , -0.66 V , -0.20V respectively and that of iron is 0.44V.In which case rusting will takes place faster when coating is damaged?

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