Which of the following electrolyte will have maximum flocculation value for Fe(OH)₃ sol ?

• NaCl

• Na₂S

• (NH₄)₃PO₄

• K₂SO₄

The time period to coat a metal surface of 80 cm² with 5 x 10^-3 cm thick layer of silver (density 1.05 g cm^-3) with the passage of 3 A current through a silver nitrate solution is

• 115 sec

• 125 sec

• 135 sec

• 145 sec

Ni/Ni²⁺ [1.0 M] || Au³⁺ [1.0 M]/Au (where E° for Ni²⁺/Ni  is -0.25 V E° for Au³⁺/Au is 0.150 V)

Whar is the emf of the cell ?

• + 0.4 V

• - 1.75 V

• + 1.25 V

• + 1.75 V

The specific conductance of a N/ 10 KCl at 25°C is 0.0112 ohm^-1cm^-1.The resistance of cell containing solution at the same temperature was found to be 55 ohm. The cell constant will be

• 6.16 cm^-1

• 0.616 cm^-1

• 0.0616 cm^-1

• 616 cm^-1

In acidic medium MnO₄^2- is converted to Mn²⁺ .The quantity of electricity in faraday required to reduce 0.5 mole of MnO₄^2- to Mn²⁺ would be :

• 2.5

• 1

• 5

• 0.5

During electrolysis of water the volume of oxygen liberated is 2.24 dm³ .The volume of hydrogen liberated , under same conditions will be :

• 2.24 dm³

• 1.12 dm³

• 4.48 dm³

• 0.56 dm³

In a lead storage battery , reaction at cathode is :

• Pb + SO₄^2- $\to$ PbSO₄ + 2e^-

• Pb + PbO₂ + 2H₂SO₄ $\to$ 2PbSO₄ + 2H₂O

• PbSO₄ + 2e^- $\to$ Pb + SO₄^2-

• PbO₂ + 4H⁺ + SO₄^2- + 2e^- $\to$ PbSO₄ + 2H₂O

If hydrogen electrode dipped in two-solution of pH = 3 and pH = 6 and salt bridge is connected , the emf of resulting cell is :

• 0.177 V

• 0.3 V

• 0.052 V

• 0.104 V

699.

If the Zn²⁺/Zn electrode is diluted to 100 times then the change in emf :

• increase of 59 mV

• decrease of 59 mV

• increase of 29.5 mV

• decrease of 29.5 mV

If equivalent conductance of 1 M benzoic acid is 12.8 ohm^-1 cm and if the conductance of benzoate ion and H⁺ ion are 42 and 288 .42 ohm^-1 cm² respectively .Its degree of dissociation is :

• 39 %

• 3.9 %

• 0.35 %

• 0.039 %