Answer
The two charges are 30 km apart.
Work Step by Step
We can find the separation distance between the two charges:
$F = \frac{k~q_1~q_2}{r^2}$
$r^2 = \frac{k~q_1~q_2}{F}$
$r = \sqrt{\frac{k~q_1~q_2}{F}}$
$r = \sqrt{\frac{(9.0\times 10^9~N~m^2/C^2)(1~C)(1~C)}{10~N}}$
$r = 3.0\times 10^4~m$
$r = 30~km$
The two charges are 30 km apart.
