Answer
$\sqrt 12\approx3.464$ units
Work Step by Step
We know that the distance $d$ between two points $(x_{1},y_{1})$ and $x_{2},y_{2})$ is given by $d=\sqrt ((x_{2}-x_{1})^{2}+(y_{2}-y_{1})^{2})$.
Therefore, the distance between $(-\sqrt 5,0)$ and $(0, \sqrt 7)$ will be $d=\sqrt ((0-(-\sqrt 5))^{2}+(\sqrt 7-0)^{2})=\sqrt ((\sqrt 5)^{2}+(\sqrt 7)^{2})=\sqrt (5+7)=\sqrt 12\approx3.464$ units