The molar conductivity of an electrolyte solution is 2.5 × 10−2 S m2 mol−1. What is its value in S cm2 mol−1?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 250 S cm2 mol−1
The unit has an area term, m2. Since 1 m = 100 cm, 1 m2 = (100 cm)2 = 104 cm2, so 1 S m2 mol−1 = 104 S cm2 mol−1.
\( \displaystyle \Lambda_m = 2.5 \times 10^{-2}\ \mathrm{S\ m^2\ mol^{-1}} \times 10^{4}\ \frac{\mathrm{cm^2}}{\mathrm{m^2}} \)
\( \displaystyle \Lambda_m = 2.5 \times 10^{2}\ \mathrm{S\ cm^2\ mol^{-1}} = 250\ \mathrm{S\ cm^2\ mol^{-1}} \)
NCERT (2026-27 edition):
2.4.1 Measurement of the Conductivity of Ionic Solutions – “Both type of units are used in literature and are related to each other by the equations: 1 S m2mol–1 = 104 S cm2mol–1 or 1 S cm2mol–1 = 10–4 S m2mol–1.”