Molar conductivity $\left({\Lambda }_m^{°}\right)$ at infinite dilution of NaCl, HCl and $C{H}_{3}COONa$ are 126.4, 425.9 and $91.0 S c{m}^{2}mo{l}^{-1}$ respectively $\left({\Lambda }_m^{°}\right)$ for $C{H}_{3}COOH$  will be

${\Lambda }_{NaCl}^{°}=126.4Sc{m}^{2}mo{l}^{-1}$

${\Lambda }_{HCl}^{°}=425.9Sc{m}^{2}mo{l}^{-1}$

${\Lambda }_{C{H}_{3}COONa}^{°}=91.0Sc{m}^{2}mo{l}^{-1}$

$\begin{array}{l}{\Lambda }_{C{H}_{3}COOH}^{°}={\Lambda }_{C{H}_{3}COONa}^{°}+{\Lambda }_{HCl}^{°}-{\Lambda }_{NaCl}^{°}\\ =91.0+425.9-126.4\\ =390.5c{m}^{2}mo{l}^{-1}\end{array}$