Electrochemistry Chemistry MCQ Practice Tests: Free Quiz

A quantity of electricity liberates 5600 mL of O2 at STP. What mass of Ag (atomic mass 108) can be deposited by the same charge?

A. 5.4 g
B. 10.8 g
C. 54.0 g
D. 108.0 g

A galvanic cell has E∘=0.295 V at 25°C and involves transfer of 2 electrons. The equilibrium constant is approximately:

A. 2.0×10^{11}
B. 4.0×10^{12}
C. 1.0×10^2
D. $1.0\times 10^10$

Cobalt(II) chloride solution is electrolysed using 10 A for 109 minutes. Given 96,500 C mol⁻¹ and atomic mass of Co = 59, calculate the mass of cobalt deposited.

A. 1.18 g
B. 2.00 g
C. 3.54 g
D. 5.90 g

In the Hall-Héroult process, what mass of carbon anode is consumed to produce 270 kg of aluminium, assuming only CO₂ is formed?

A. 270 kg
B. 540 kg
C. 90 kg
D. 180 kg

For a pentane–oxygen fuel cell, using the standard Gibbs energies of formation of pentane, CO₂ and liquid water, the standard cell potential is:

A. 1.0968 V
B. 0.0968 V
C. 1.968 V
D. 2.0968 V

A 0.10 M NH4OH solution has molar conductance 9.54 S cm² mol⁻¹, while its limiting molar conductance is 238 S cm² mol⁻¹. Its degree of ionisation is approximately:

A. 40.8%
B. 2.08%
C. 20.8%
D. 4.008%

Kohlrausch's law states that at infinite dilution:

A. Each ion makes a definite contribution to conductance independent of the other ion
B. Each ion contributes to equivalent conductance only at finite dilution
C. Ionic contribution depends on the nature of the other ion
D. Conductance becomes zero

The theoretical maximum efficiency of a fuel cell is expressed as:

A. ΔG/ΔS\
B. ΔG/ΔH
C. ΔS/ΔG
D. $\Delta H/\Delta G$

Given limiting molar conductivities:

• NaCl = 126.4
• HCl = 425.9
• CH₃COONa = 91.0 S cm² mol⁻¹

The limiting molar conductivity of CH₃COOH is:

A. 290.8
B. 390.5
C. 425.5
D. 180.5 S cm² mol⁻¹

For a Zn–Ag₂O button cell, the standard reduction potentials are approximately:

Zn2+/Zn=−0.76V

Ag2O/Ag=+0.34V

The standard cell potential is:

A. 0.84 V
B. 1.34 V
C. 1.10 V
D. 0.42 V

The Gibbs energy required to decompose Al2O3 at 500°C is approximately +960+960 kJ mol⁻¹. The minimum potential required for electrolytic decomposition is closest to:

A. 0.99 V
B. 1.66 V
C. 2.49 V
D. 3.32 V

A hydrogen electrode operates at H2 pressure of 1 atm in an HCl solution of pH 10. Its oxidation potential is approximately:

A. 0.118 V
B. 1.18 V
C. 0.059 V
D. 0.59 V

The standard reduction potentials of X, Y and Z are −1.2 V, +0.5 V and −3.0 V, respectively. Their reducing power follows:

A. Y>Z>XY>Z>X
B. Y>X>ZY>X>Z
C. Z>X>YZ>X>Y
D. $X>Y>Z$

When 4.5 g of Al is deposited from an Al3+ solution, the same quantity of electricity liberates what volume of hydrogen at STP?

A. 44.8 L
B. 22.4 L
C. 11.2 L
D. 5.6 L

For Sn4+/Sn2, E∘=+0.15, and for Cr3+/Cr, E∘=−0.74E^=-0.74 V. The standard cell potential is: