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. The reactivity of the metal increases.

2. The reactivity of the metal decreases.

3. There is no effect on the metal's reactivity.

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. $1$ $\mathrm{x}$ ${10}^{10}$

Which of the following statements is correct for the electrolysis of CuSO₄ solution?

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.