The weight of silver (atomic weight = 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 ohm¹cm²mol^-1 and at infinite dilution its molar conductance is 238 ohm¹cm²mol^-1.

The degree of ionisation of ammonium hydroxide at the same concentration and

temperature is

1. 2.080%

2. 20.800%

3. 4.008%

4. 40.800%

A button cell used in watches functions as following

Zn(s) + Ag₂O(s) + H₂O (l) $\rightleftharpoons$2Ag(s) + Zn²⁺(aq) + 2OH^-(aq)

If half cell potentials are

$$\begin{gathered} {{\mathrm{Zn}}^{2+}}_{\left(\mathrm{aq}\right)} +\hspace{0.17em}2{\mathrm{e}}^{-} \to {\mathrm{Zn}}_{\left(\mathrm{x}\right)}; {\mathrm{E}}^{\mathrm{o}} = -0.76\mathrm{V} \\ {\mathrm{Ag}}_2{\mathrm{O}}_{\left(\mathrm{s}\right)} + {\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)} + 2{\mathrm{e}}^{-} \to 2{\mathrm{Ag}}_{\left(\mathrm{s}\right)} + 2{{\mathrm{OH}}^{-}}_{\left(\mathrm{aq}\right)}; \\ {\mathrm{E}}^{\mathrm{o}} = 0.34\mathrm{V} \end{gathered}$$

The cell potential will be

1. 0.84 V

2. 1.34 V

3. 1.10 V

4. 0.42 V

Al₂O₃ is reduced by electrolysis at low potentials and high currents. If 4.5x10⁴ A of

current is passed through molten Al₂O₃ for 6 h,what mass of aluminium is produced ?

(Assume 100% current efficiency, at. mass of Al = 27 g mol^-1)

1. 9.0 x 10³ g

2. 9.1 x 10⁴ g

3. 2.4 x 10⁵ g

4. 1.3 x 10⁴g

Standard free energies of formation (in kJ/mol) at 298 K are -237.2, -394.4 and -8.2 for H₂O(l), CO₂(g) and pentane (g), respectively. The value of E°_cell for the pentane-oxygen fuel cell is

(1) 1.968 V

(2) 2.0968 V

(3) 1.0968 V

(4) 0.0968 V

The efficiency of a fuel cell is given by:

$\left(\mathrm{a}\right) ∆\mathrm{H}/∆\mathrm{G} \left(\mathrm{b}\right) ∆\mathrm{G}/∆\mathrm{S}$
$\left(\mathrm{c}\right) ∆\mathrm{G}/∆\mathrm{H} \left(\mathrm{d}\right) ∆\mathrm{S}/∆\mathrm{G}$

A hypothetical electrochemical cell is shown below A l A⁺ (xM)l l B⁺ (yM) l B
The Emf measured is +0.20 V.The cell reaction is:-
(1) A⁺ + B → A + B⁺

(2) A⁺ + e^- →  A ; B⁺ + e^- → B

(3) the cell reaction cannot be predicted

(4) A + B⁺ → A⁺ + B

The E° in the given diagram is,

(1) 0.5

(2) 0.6

(3) 0.7

(4) 0.8

At 298K the standard free energy of formation of H₂O(l) is –237.20kJ/mole while that of its ionisation into H+ iion and hydroxyl ions is 80 kJ/mole, then the emf of the following cell at 298 K will be

H₂(g,1 bar) | H⁺ (1M) || OH^–(1M) | O₂ (g, 1bar)

(1) 0.40 V

(2) 0.81 V

(3) 1.23 V

(4) –0.40 V

Which of the following cell can produce more electric work.

(1) pt,H₂|NH₄Cl||0.1MCH₃COOH|H₂,pt

(2) pt,H₂|0.1MHCl||0.1MNaOH|H₂,pt

(3) pt,H₂|0.1MHCl||0.1MCH₃COOK|H₂,pt

(4) pt,H₂|0.1MCH₃COOK||0.1MHCl|H₂,pt