Two spheres of electric charges +2 nC and -8 nC are placed at a distance $d$ apart. If they are allowed to touch each other, what is the new distance between them to get a repulsive force of same magnitude as before?

Three point charges of $+2 q,+2 q$ and $-4 q$ are placed at the corners $A, B$ and $C$ of an equilateral triangle $A B C$ of side $x$. The magnitude of the electric dipole moment of this system is