At what distance of separation must two 1.00-microCoulomb charges be positioned in order for the repulsive force between them to be equivalent to the weight (on Earth) of a 1.00-kg mass?

##30,3mm##

From of Electrostatic forces between charged objects we get that

##F=k(Q_1Q_2)/r^2##

##therefore r = sqrt((kQ_1Q_2)/F)##

##=sqrt((9xx10^9)(1xx10^(-6))^2)/(9,8)##

##=30,3mm##

(Note that the weight force is given by ##W=mg=1xx9,8=9,8N##)