Match List-I with List-II
| List-I | List-II |
| Quantity | Units |
| (A) Conductivity | (I) ohm |
| (B) Molar Conductivity | (II) S |
| (C) Resistance | (III) S cm−1 |
| (D) Conductance | (IV) S cm2 mol−1 |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A) - (III), (B) - (IV), (C) - (I), (D) - (II)
All four quantities come from the resistance of a conductor of length l and area of cross section A. Each one is the inverse of another, or is divided by the concentration, so its unit follows from the one before it:
\( \displaystyle R=\rho\frac{l}{A},\qquad G=\frac{1}{R},\qquad \kappa=\frac{1}{\rho},\qquad \Lambda_m=\frac{\kappa}{c} \)
(A) Conductivity — This matches (III) S cm−1. Conductivity (κ) is the inverse of resistivity. Resistivity is measured in Ω cm, so κ is in Ω−1 cm−1 = S cm−1 (SI unit S m−1).
(B) Molar Conductivity — This matches (IV) S cm2 mol−1. Molar conductivity is the conductivity divided by the molar concentration. With κ in S cm−1 and c in mol cm−3:
\( \displaystyle \Lambda_m=\frac{\mathrm{S\,cm^{-1}}}{\mathrm{mol\,cm^{-3}}}=\mathrm{S\,cm^{2}\,mol^{-1}} \)
(C) Resistance — This matches (I) ohm. Resistance (R) is the opposition to the flow of current and is measured in ohm (Ω).
(D) Conductance — This matches (II) S. Conductance (G) is the inverse of resistance, so its unit is ohm−1, called the siemens (S).
NCERT (2026-27 edition):
Conductance of Electrolytic Solutions – “… The electrical resistance is represented by the symbol ‘R’ and it is measured in ohm (Ω) … The inverse of resistance, R, is called conductance, G, … The SI unit of conductance is siemens, represented by the symbol ‘S’ and is equal to ohm–1 (also known as mho) or Ω–1. The inverse of resistivity, called conductivity (specific conductance) is represented by the symbol, κ (Greek, kappa). IUPAC has recommended the use of term conductivity over specific conductance and hence we shall use the term conductivity in the rest of the book. The SI units of conductivity are S m–1 but quite often, κ is expressed in S cm–1.”
Measurement of the Conductivity of Ionic Solutions – “… It, therefore, becomes necessary to define a physically more meaningful quantity called molar conductivity denoted by the symbol Λm (Greek, lambda). … If we use S cm–1 as the units for κ and mol cm–3, the units of concentration, then the units for Λm are S cm2 mol–1.”