The ${\mathrm{\Lambda }}^{\circ }$ of ${\mathrm{NH}}_4\mathrm{Cl}\text{, }$NaOH and NaCl are 129.8, 217.4 and $108.9{\mathrm{ohm}}^{-1}{\mathrm{cm}}^2{\mathrm{mol}}^{-1}$ respectively. The ${\mathrm{\Lambda }}^{\circ }$ of ${\mathrm{NH}}_4\mathrm{OH}$ is ....${\mathrm{ohm}}^{-1}{\mathrm{cm}}^2{\mathrm{mol}}^{-1}$