Pairs of reactants (R) and product (P) are given below. The pair which can be used in a fuel cell is :

1. $R\mathit{=}{H}_{\mathit{2}\mathit{\left(}\mathit{g}\mathit{\right)}}\mathit{,}{O}_{\mathit{2}\mathit{\left(}\mathit{g}\mathit{\right)}}\mathit{;}P\mathit{=}{H}_{\mathit{2}}{O}_{\mathit{2}\mathit{\left(}\mathit{g}\mathit{\right)}}$

2. $\mathrm{R}={\mathrm{H}}_{2\left(\mathrm{g}\right)},{\mathrm{O}}_{2\left(\mathrm{g}\right)};\mathrm{P}={\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{\ell }\right)}$

3. $\mathrm{R}={\mathrm{H}}_{2\left(\mathrm{g}\right)},{\mathrm{O}}_{2\left(\mathrm{g}\right)},{\mathrm{Cl}}_{2\left(\mathrm{g}\right)};\mathrm{P}={\mathrm{HClO}}_{4\left(\mathrm{aq}\right)}$

4. $\mathrm{R}={\mathrm{H}}_{2\left(\mathrm{g}\right)},{\mathrm{N}}_{2\left(\mathrm{g}\right)};\mathrm{P}={\mathrm{NH}}_{3\left(\mathrm{aq}\right)}$

The negative sign in the expression E^o_Zn²⁺/Zn = -0.76 V indicates : 

1. Metal reactivity increases.

2. Metal reactivity decreases.

3. No effect on metal.

4. None of the above.

Electrode potential is the potential difference between the -

1. Electrode and the electrolyte.

2. Anode and Cathode.

3. Anode and Atmosphere.

4. Cathode and Atmosphere.

The resistance of a conductivity cell containing 0.001M KCl solution at 298 K is 1500 Ω. The cell constant if conductivity of 0.001 M KCl solution at 298 K is 0.146 ×10^-3  S cm^-1 will be: 

1. 0.32 cm^-1

2. 0.47 cm

3. 0.22 cm^-1

4. 0.23 cm

The conductivity of 0.00241 M acetic acid is 7.896 × 10^–5 S cm^–1. If ${\mathrm{\Lambda }}_{\mathrm{m}}^0$ for acetic acid is 390.5 S cm² mol^–1, the dissociation constant will be 
1. \(2.45 \times 10^{-5} \mathrm{~mol} \ \mathrm{~L}^{-1} \)
2. \(1.86 \times 10^{-5} \mathrm{~mol} \ \mathrm{L^{-1}} \)
3. \(3.72 \times 10^{-5}\mathrm{~mol} \mathrm{~L^{-1}} \)
4. \(2.12 \times 10^{-5}\mathrm{~mol} \mathrm{~L^{-1}}\)

One liter of 0.5 M KCl solution is electrolyzed for one minute in a current of 1.608 mA. Considering 100 % efficiency, the pH of the resulting solution will be : 

Molten sodium chloride conducts electricity due to the presence of : 

1. Free ions.

2. Free molecules.

3. Free electrons.

4. Atoms of sodium and chlorine.

At $25°\mathrm{C}$, the standard emf of a cell reaction involving a two-electron exchange is found to be 0.295 V. The equilibrium constant of the reaction is approximately : 

1. $9.50\times {10}^9$

2. $9.51\times {10}^7$

3. 10

4. $1$ $\mathrm{x}$ ${10}^{10}$

For the electrolysis of CuSO₄ solution the correct option is: 

1. Cathode reaction: Cu²⁺ + 2e^- $\to$ Cu using Cu electrode.

2. Anode reaction: Cu $\to$ Cu⁺ + e^- using Cu electrode.

3. Cathode reaction: 2H⁺ + 2e^- $\to$H₂ using Pt electrode.

4. Anode reaction: Cu $\to$ Cu²⁺ + 2e^- using Pt electrode.