The value of ${\wedge }_{\mathrm{m}}^{\infty }$ for KCl and ${\mathrm{KNO}}_3$ are 149.86 and $154.96{\mathrm{\Omega }}^{-1}{\mathrm{Cm}}^2 {\mathrm{mol}}^{-1}$ Also ${\mathrm{\lambda }}_{{\mathrm{cl}}^{-}}^{\infty }$  is 71.44 ${\mathrm{ohm}}^{-1}{\mathrm{cm}}^2 {\mathrm{mol}}^{-1}$ The value of ${\mathrm{\lambda }}_{{\mathrm{NO}}_3^{-}}^{\infty }$ is

${\mathrm{\lambda }}_{\mathrm{M}}^{\infty }\to {\mathrm{KNO}}_3={\mathrm{\lambda }}_{\mathrm{M}\left({\mathrm{K}}^{+}\right)}+{\mathrm{\lambda }}_{\mathrm{M}\left({\mathrm{NO}}_3^{-}\right)}=154.96$

${\mathrm{\lambda }}_{\mathrm{M}}^{\infty }\to \left(\mathrm{KCl}\right)={\mathrm{\lambda }}_{\mathrm{M}\left({\mathrm{K}}^{+}\right)}+{\mathrm{\lambda }}_{\mathrm{M}\left({\mathrm{cl}}^{-}\right)}=149.86$

${\mathrm{\lambda }}_{\mathrm{M}\left({\mathrm{K}}^{+}\right)}+71.44=149.86$

${\mathrm{\lambda }}_{\mathrm{M}\left({\mathrm{K}}^{+}\right)}149.86-71.44$

=78.42

$\therefore 78.42+{\mathrm{\lambda }}_{\mathrm{M}\left({\mathrm{NO}}_3^{-}\right)}=154.96$

${\mathrm{\lambda }}_{\mathrm{M}\left({\mathrm{NO}}_3^{-}\right)}=154.96-78.42$

$=76.54$