∧ m o for NaCl ,   HCl and NaA are 126.4 ,   425.9 and 100 .5   S   cm 2 mol -…

Kohlrausch's law states that the equivalent conductivity of an electrolyte at infinite dilution is equal to the sum of the conductances of the anions and cations.

${\mathrm{\lambda }}_{\mathrm{m}}^{\mathrm{o}}\left(\mathrm{HA}\right)={\mathrm{\lambda }}_{\mathrm{m}}^{\mathrm{o}}\left(\mathrm{HCl}\right)+{\mathrm{\lambda }}_{\mathrm{m}}^{\mathrm{o}}\left(\mathrm{NaA}\right)-{\mathrm{\lambda }}^{\mathrm{o}}\left(\mathrm{NaCl}\right)$

$=425.9+100.5-126.4$

$=400$

${\mathrm{\lambda }}_{\mathrm{m}}^{\mathrm{o}}=\frac{\mathrm{K}\times 1000}{\mathrm{M}}=\frac{5\times {10}^{-5}\times {10}^3}{{10}^{-3}}=50$

$\mathrm{\alpha }=\frac{50}{400}=0.125$