Electrochemistry

The number of electrons delivered at the cathode during electrolysis by a current of 1 ampere in 60 seconds is (charge on electron = 1.60 10-19 C)

1. 6 1023
2. 6 1020
3. 3.75 1020
4. 7.48 1023

Zinc can be coated on iron to produce galvanized iron but the reverse is not possible. It is because

1. zinc is lighter than iron
2. zinc has lower melting point than iron
3. zinc has lower negative electrode potential than iron
4. zinc has higher negative electrode potential than iron

Aqueous solution of which of the following compounds is the best conductor of electric current ?

1. Hydrochloric acid, HCl
2. Ammonia, NH3
3. Fructose, C6H12O6
4. Acetic acid, C2H4O2

A device that converts energy of combustion of fuels like hydrogen and methane, directly into electrical energy is known as

1. dynamo
2. Ni-Cd cell
3. fuel cell
4. electrolytic cell

When 0.1 mol MnO42- is oxidised the quantity of electricity required to completely oxidise MnO42- to MnO4- is

1. 96500 C
2. 2 96500 C
3. 9650 C
4. 96.50 C

The weight of silver (at. wt. = 108) displaced by a quantity of electricity which displaces 5600 mL of O2 at STP will be

1. 5.4 g
2. 10.8 g
3. 54.0 g
4. 108.0 g

At 25 C molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is 9.54 ohm-1 cm2 mol-1 and at infinite dilution its molar conductance is 238 ohm-1 cm2 mol-1. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is

1. 4.008\%
2. 40.800\%
3. 2.080\%
4. 20.800\%

A button cell used in watches functions as follows. Zn(s) + Ag2O(s) + H2O(l) 2Ag(s) + Zn2+(aq) + 2OH-(aq) If half cell potentials are Zn2+(aq) + 2e- Zn(s); E = -0.76 V Ag2O(s) + H2O(l) + 2e- 2Ag(s) + 2OH-(aq), E = 0.34 V The cell potential will be

1. 0.84 V
2. 1.34 V
3. 1.10 V
4. 0.42 V

A hydrogen gas electrode is made by dipping platinum wire in a solution of pH = 10 and by passing hydrogen gas around the platinum wire at one atm pressure. The oxidation potential of electrode would be

1. 0.118 V
2. 1.18 V
3. 0.059 V
4. 0.59 V

Consider the half-cell reduction reaction Mn2+ + 2e- Mn, E = -1.18 V Mn2+ Mn3+ + e-, E = -1.51 V The E for the reaction 3Mn2+ Mn + 2Mn3+, and possibility of the forward reaction are respectively

1. -4.18 V and yes
2. +0.33 V and yes
3. +2.69 V and no
4. -2.69 V and no