# Physical Chemistry Questions and Answers – Electrical Conductivity

This set of Physical Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Electrical Conductivity”.

1. Electrical Conductivity is also known as pressure resistivity.
a) False
b) True

Explanation: Electrical Conductivity is also known as Volume resistivity, resistivity or specific electrical resistance. It is represented by rho.

2. Electrical conductivity is the reciprocal of Electrical resistivity.
a) True
b) False

Explanation: It is the reciprocal of electrical conductivity. It can be defined as the measure of material’s ability to conduct an electric current.

3. Electrical conductivity can be represented as:
a) ρ
b) Ω
c) σ
d) S

Explanation: Electrical conductivity is represented as σ. It can also be represented as k (kappa) or γ (gamma) occasionally.

4. What is the SI unit of electrical resistivity?
a) Ω – m
b) Ω
c) m/s
d) K

Explanation: Ω – m is the SI unit of the electrical resistivity. A low resistivity of the material shows that the material readily allows the flow of electric current.

5. What is the CGS unit of electrical conductivity?
a) Ω – m
b) s-1
c) m
d) Ω

Explanation: (S/m) siemens per meter is the SI unit of electrical conductivity and second inverse (s-1) is the CGS unit of electrical conductivity.

6. Which one of the following is correct for the mathematical representation of electrical resistivity?
a) ρ = (R l/A)
b) ρ = R A
c) ρ = 0
d) ρ = l

Explanation: The electrical conductivity can be defined mathematically as ρ = (R l/A) where R is the electrical resistance, l is the length and A is the cross-sectional area.

7. What is the Fermi level?
a) The sum of the entropies of thermodynamic system increases
b) When energy passes the system’s internal energy changes
c) Chemical potential for electrons
d) The entropy of the system at absolute zero is close to zero

Explanation: Fermi level can be defined as the chemical potential or electrochemical potential for the electrons. It is denoted by EF.

8. Calculate E0cell of (at 298 K), Zn(s) / ZnSO4(aq) ll CuSO4(aq) / Cu(s).
a) 4.1 V
b) 3.1 V
c) 2.1 V
d) 1.1 V

Explanation: E0Zn/Zn2+(aq) = 0.76 V, E0Cu(s) / Cu2+(aq) = -0.34 V. So, E0cell = (S.R.P)cathode – (S.R.P)anode = 0.34 – (- 0.76) = 1.1 V.

9. If resistivity of 8.0 M KCl is 2.5 * 103 Ω m calculate the molar conductivity of the solution.
a) 5 Ω-1 cm2 mole-1
b) 5 * 105 Ω-1 cm2 mole-1
c) 4 * 105 Ω-1 cm2 mole-1
d) 4 Ω-1 cm2 mole-1

Explanation: ρ = 2.5 * 10-3 Ω cm. K = 103/2.5 = 4 * 102. Molar conductivity is denoted by Λm. So, Λm = (4 * 102 * 1000 * 10)/0.8 = 5 * 105 Ω-1 cm2 mole-1.

Sanfoundry Global Education & Learning Series – Physical Chemistry.

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