The figure shows the plot of the molar conductivity (Λm) of KCl solut…

The correct answer is Option (1) → 150.0 S cm² mol⁻¹

For a strong electrolyte such as KCl, Λ_m = Λ°_m when c^1/2 = 0, so Λ°_m is the intercept of the line on the Λ_m axis:

    \( \Lambda_m = \Lambda_m^{\circ} - A\,c^{1/2} \)

In the figure, the line meets the Λ_m axis (c^1/2 = 0) at 150.0 S cm² mol⁻¹.

    Λ°_m(KCl) = 150.0 S cm² mol⁻¹

NCERT (2026-27 edition):
2.4.2 Variation of Conductivity and Molar Conductivity with Concentration – “…It can be seen that if we plot (Fig. 2.6) Λ_m against c^1/2, we obtain a straight line with intercept equal to Λ°_m and slope equal to ‘–A’.”

Example 2.6 – “…A plot of Λ_m (y-axis) and c^1/2 (x-axis) is shown in (Fig. 2.7). It can be seen that it is nearly a straight line. From the intercept (c^1/2 = 0), we find that Λ°_m = 150.0 S cm² mol^–1 and A = – slope = 87.46 S cm² mol^–1/(mol/L^–1)^1/2.”

Fig. 2.7: Variation of Λ_m against c½.