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

When 0.1 mol MnO₄^2– is oxidized, the quantity of electricity required to completely oxidise MnO₄^2– 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

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

The cell potential will be:

Limiting molar conductivity of NH₄OH (i.e., ${\mathrm{\Lambda }}_{\mathrm{m}\left({\mathrm{NH}}_4\mathrm{OH}\right)}^0$ is equal to -

1. ${\mathrm{\Lambda }}_{\mathrm{m}\left(\mathrm{NaOH}\right)}^0+{\mathrm{\Lambda }}_{\mathrm{m}\left(\mathrm{NaCl}\right)}^0-{\mathrm{\Lambda }}_{\mathrm{m}\left(\mathrm{NaOH}\right)}^0$

2. ${\mathrm{\Lambda }}_{\mathrm{m}\left(\mathrm{NaOH}\right)}^0+{\mathrm{\Lambda }}_{\mathrm{m}\left(\mathrm{NaCl}\right)}^0-{\mathrm{\Lambda }}_{\mathrm{m}\left({\mathrm{NH}}_4\mathrm{Cl}\right)}^0$

3. ${\mathrm{\Lambda }}_{\mathrm{m}\left({\mathrm{NH}}_4\mathrm{OH}\right)}^0+{\mathrm{\Lambda }}_{\mathrm{m}\left({\mathrm{NH}}_4\mathrm{Cl}\right)}^0-{\mathrm{\Lambda }}_{\mathrm{m}\left(HCl\right)}^0$

4. ${\mathrm{\Lambda }}_{\mathrm{m}\left({\mathrm{NH}}_4\mathrm{Cl}\right)}^0+{\mathrm{\Lambda }}_{\mathrm{m}\left(\mathrm{NaOH}\right)}^0-{\mathrm{\Lambda }}_{\mathrm{m}\left(\mathrm{NaCl}\right)}^0$

The Gibb's energy for the decomposition of \(\mathrm{A l_{2} O_{3}}\) at \(\mathrm{500~ ^\circ C}\) is as follows: 

2/3Al₂O₃ → 4/3Al + O₂ ; ∆_rG = + 960 k J mol^–1

The potential difference needed for the electrolytic reduction of aluminium oxide (Al₂O₃) at \(\mathrm{500~ ^\circ C}\) is at least,

1. 3.0 V 

2. 2.5 V 

3. 5.0 V 

4. 4.5 V