The excess pressure inside a liquid drop is 500 Nm^-2. If the radius of the drop is 2 mm, the surface tension of liquid is x × 10^-3 Nm^-1. The value…

The excess pressure inside a liquid drop is $\displaystyle 500 \mathrm{Nm}^{-2}$. If the radius of the drop is $\displaystyle 2$ mm, the surface tension of liquid is $\displaystyle x \times 10^{-3} \mathrm{Nm}^{-1}$. The value of $\displaystyle x$ is \_\_\_\_.