The specific conductance of $0.0025 ~\mathrm{M}$ acetic acid is $5 \times 10^{-5} \mathrm{~S} \mathrm{~cm}^{-1}$ at a certain temperature. The dissociation constant of acetic acid is __________ $\times ~10^{-7}$ (Nearest integer)

Consider limiting molar conductivity of $\mathrm{CH}_{3} \mathrm{COOH}$ as $400 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$