Electrochemistry

The reaction at cathode in the cells commonly used in clocks involves.

1. oxidation of Mn from +2 to +7
2. reduction of Mn from +4 to +3
3. oxidation of Mn from +3 to +4
4. reduction of Mn from +7 to +2

The quantity of silver deposited when one coulomb charge is passed through AgNO3 solution :

1. 0.1 g atom of silver
2. 1 chemical equivalent of silver
3. 1 g of silver
4. 1 electrochemical equivalent of silver

For the electrochemical cell M | M2+ || X | X2- If E0(M2+/M) = 0.46 V and E0(X/X2-) = 0.34 V. Which of the following is correct?

1. Ecell = 0.80 V
2. M + X M2+ + X2- is a spontaneous reaction
3. Ecell = -0.80 V
4. M2+ + X2- M + X is a spontaneous reaction

One of the commonly used electrode is calomel electrode. Under which of the following categories, calomel electrode comes?

1. Metal ion - Metal electrodes
2. Oxidation - Reduction electrodes
3. Metal - Insoluble Salt - Anion electrodes
4. Gas - Ion electrodes

What pressure (bar) of H2 would be required to make emf of hydrogen electrode zero in pure water at 25 ?

1. 0.5
2. 10-14
3. 1
4. 10-7

Fuel cell, using hydrogen and oxygen as fuels, Choose the correct answer from the options given below:

1. A, D, E only
2. A, B, C only
3. A, B, D only
4. A, B, D, E only

For a strong electrolyte, a plot of molar conductivity against (concentration)1/2 is a straight line, with a negative slope, the correct unit for the slope is

1. S cm2 mol-3/2 L
2. S cm2 mol-3/2 L-1/2
3. S cm2 mol-1 L1/2
4. S cm2 mol-3/2 L1/2

The potential for the given half cell at 298 K is (-) 10-2 V 2H+(aq) + 2e- H2(g) [H+] = 1 M, PH2 = 2 atm (Given : 2.303 RT/F = 0.06 V, 2 = 0.3)

The amount of electricity in Coulomb required for the oxidation of 1 mol of H2O to O2 is 105 C.

Consider the following redox reaction : MnO4- + H+ + H2C2O4 Mn2+ + H2O + CO2 The standard reduction potentials are given as below ( E0red ) : E MnO4-/Mn2+ = +1.51 V E CO2/H2C2O4 = -0.49 V If the equilibrium constant of the above reaction is given as Keq = 10x, then the value of x = (nearest integer)