A device that converts energy of the combustion of fuels like hydrogen and methane, directly

into electrical energy is known as:

1. Fuel cell

2. Electrolytic cell

3. Dynamo

4. Ni-Cd cell

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

current?

1. Acetic acid, C₂H₄O₂

2. Hydrochloric acid, HCl

3. Ammonia, NH₃

4. Fructose, C₆H₁₂O₆

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

Limiting molar conductivity of NH₄OH (i.e Åm(NH₄OH)) is equal to:-

1. Å_m (NH₄Cl)+Å_m(NaCl)-Å_m(NaOH) 

2. Å_m(NaOH)+Å_m(NaCl)-Å_m(NH₄Cl)

3. Å_m(NH₄OH)+Å_m(NH₄Cl)-Å_m(HCl)

4. Å(NH₄Cl)+Å(NaOH)-Å(NaCl)

Kohlrausch's law states that at

(1) finite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte, whatever be the nature of the other ion of the electrolyte.

(2) infinite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte depending on the nature of the other ion of th electrolyte.

(3) infinite dilution, each ion makes definite contribution to conductance of an electrolyte whatever be the nature of the other ion of the electrolyte.

(4) infinite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte, whatever be the nature of the other ion of the electrolyte.

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 equilibrium constant of the reaction:

Cu (s) + 2Ag⁺ (aq) $\to$Cu²⁺ (aq) + 2Ag(s) ;

E^o = 0.46 V at 298 K is:

The efficiency of a fuel cell is given by:

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